if you are running a 20g setup then run 3" piping, even with a cutout you may not get the right back presure. thats the whole key in doing any exhaust work is not going to big and not going to small. you could maybe get away with a catback or a turboback, how much boost are you planning on running?

2GxJBxDSM said:

if you are running a 20g setup then run 3" piping, even with a cutout you may not get the right back presure. thats the whole key in doing any exhaust work is not going to big and not going to small. you could maybe get away with a catback or a turboback, how much boost are you planning on running?

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Well first off, it's not back pressure, it's the scavenging effect. Second, exhaust size doesn't matter nearly as much on a turbo'd vehicle as it does on an all motor, bigger is just usually better.

IMO the op should go with 3", as you are not likely to outgrow that setup, even with a 20g.

manifestmessiah said:

Well first off, it's not back pressure, it's the scavenging effect. Second, exhaust size doesn't matter nearly as much on a turbo'd vehicle as it does on an all motor, bigger is just usually better.

IMO the op should go with 3", as you are not likely to outgrow that setup, even with a 20g.

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is wrong with you..How does exahust size not matter nearly as much on a turbo car..

Try getting the same power on a 2.25 stock exhaust as you would on a 4 inch..

People have put the cutout on their stock exhaust, and notice a huge difference..

Bud92gsx said:

is wrong with you..How does exahust size not matter nearly as much on a turbo car..

Try getting the same power on a 2.25 stock exhaust as you would on a 4 inch..

People have put the cutout on their stock exhaust, and notice a huge difference..

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I meant you don't have to try to tune for the best scavenging effect, that bigger is usually better.

Ok good..You may want to relay that in your posts next time..Thats how you end up with red chicklets.

Now even repacing the flex pipe on a s tock dsm with a cutout..Your going to notice a difference when the cutout opens..

I have a 3 inch..If I take my caback off the car, and run open DP..U can can hear difference..I knew the difference when I swapped form stock exhaust..

Just trying to help the OP and you, get it right is all.

Just get 3 inch turbo back exhaust and call it a day. Unless you like noise. Power gains will be so minimal not even to worry about.

clipto said:

Just get 3 inch turbo back exhaust and call it a day. Unless you like noise. Power gains will be so minimal not even to worry about.

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exactly. you will save so much time and effort

Guys, not sure where this time and effort thing is coming from. Also not sure about the minimal power gains. I once gained 14hp on a n/a vehicle when everyone was saying that power gains would be minimal. As before, I don't care about noise. This is not my DD. Also, installing the cutout will actually save me plenty of time and effort plus plenty of money.

It is not just like I can go to ebay and get a decent catback for cheap either. This is a Galant VR-4 we are talking about.

An open cutout will cost me $30 plus shipped. All that I have to do is cutout the damaged exhaust area and put the cutout in it's place.

To me, the cutout is a no brainer except for the million dollar question. Does a 3 inch exhaust flow that much better than a 2.5 inch exhaust with a cutout?

Would a 2.5" exhaust with a cutout be sufficient for a 20g at higher boost? I don't have to like what you are telling me but the answers should be more technical and precise.

Thanks

Use 3 inch pipe the cost to make the piping and buy the cut out is about the same

hector1147 said:

Use 3 inch pipe the cost to make the piping and buy the cut out is about the same

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That makes no sense. Buying 3 inch pipe and a Mig Welder plus bending the tubes with tools I don't even know about etc etc...or paying the labor (you'd better be loaded to have a good welder touch your car or have any respect for it around here since they aren't even smart enough to know what a turbo is) how is that cheaper than a cutout?

No one really answered this guy's question as he was specifically refering. He asked which cutout flows more gas and therefore would be more efficient or inefficient for his setup with all things considered. But truthfully a 2.5" cutout before the cat would flow as much as a 3" catted full exhaust system and a 3" cutout exhaust before the cat would flow as much as a 3.5" catted full exhaust system. Hope this helps out bro.

10's or bust said:

No one really answered this guy's question as he was specifically refering to is which cutout flows more gas therefore a would be more efficient or inefficient for his se.tup with all things considered. But truthfully a 2.5" cutout before the cat would flow as much as a 3" catted full exhaust system and a 3" cutout exhaust before the cat would flow as much as a 3.5" catted full exhaust system. Hope this helps out bro.

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Thanks for the help. I did make one mistake when I said *neither* in my first post I meant *either*.

So my question is for hi-flow catted exhausts.

Let me try and simplify my question and get away from the 20g stuff for now.

Would a 3 inch downpipe back exhaust with a high flow cat/performance muffler outflow a 2.5inch downpipe back exhaust with a highflow cat and an open cutout?

blkchr91 said:

Thanks for the help. I did make one mistake when I said *neither* in my first post I meant *either*.

So my question is for hi-flow catted exhausts.

Let me try and simplify my question and get away from the 20g stuff for now.

Would a 3 inch downpipe back exhaust with a high flow cat/performance muffler outflow a 2.5inch downpipe back exhaust with a highflow cat and an open cutout?

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No one is really going to be able to give you a solid answer because this is such a random circumstance that probably hasn't been tested. If it were me, I would just do the 3" exhaust from the turbo back. I think either way will work though so if its cheaper to do the cut out just do it. If there is going to be power gains or loses in either setup, they will be minimal.

richard33 said:

No one is really going to be able to give you a solid answer because this is such a random circumstance that probably hasn't been tested. If it were me, I would just do the 3" exhaust from the turbo back. I think either way will work though so if its cheaper to do the cut out just do it. If there is going to be power gains or loses in either setup, they will be minimal.

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Sounds reasonable, thanks. $500 vs $37 shipped for the cutout. I think I have enough to go on here.

blkchr91 said:

Sounds reasonable, thanks. $500 vs $37 shipped for the cutout. I think I have enough to go on here.

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ya man. I've had a mechanical cutout and now I have an E-cutout. The mechanical one sucks for obvious reasons of having to crawl under the car and take the plate off every time you want to open it. The electrical cutout sucks just as much though . They are more expensive and go bad quickly. Mine doesn't seal anymore and rattles loudly. But minor things that can be easily over looked for the performance gains. I have my cutout connected to a stock catback so just driving around you would never know my car makes over 600whp until I open the cut out

richard33 said:

ya man. I've had a mechanical cutout and now I have an E-cutout. The mechanical one sucks for obvious reasons of having to crawl under the car and take the plate off every time you want to open it. The electrical cutout sucks just as much though . They are more expensive and go bad quickly. Mine doesn't seal anymore and rattles loudly. But minor things that can be easily over looked for the performance gains. I have my cutout connected to a stock catback so just driving around you would never know my car makes over 600whp until I open the cut out

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I can relate, used to live in the Fort Lauderdale area when younger and ran my cutout uncorked at all times. No cops ever bothered me, but was pulled over all the time for speed etc. Up here it is a different game, but I hardly drive the Galant. Not comfy parking it in DC overnight if I can avoid it. That is what my daily is for.

Anyways, they love to try to toss you in jail for reckless driving over here...anything over 80+ is considered reckless here...and radar detectors are illegal so getting stopped for an exhaust cutout should be no big deal if it were to happen.

I'd not live here but for the fact that there are so many jobs.

cutouts imo are a complete waste of time just go with a 3 inch tbe with a muffler and a cat if you have too (i dont) and also run a open dump wastegate that will work just fine no need to jank up another dsm do it right and do it once

Obviously a nice 3" turboback is your best solution. Maybe not your most cost effective as you stated.

Ideally you should have your cutout as close to the turbo as you could. If you could get it placed right after the flex in the downpipe would be ideal. Placing it directly after your biggest restriction in your exhaust system, your cat, while it won't hurt, its not the best spot for it.

If you had the cutout right after the flex, then i'd say you have plenty of exhaust flow to support the 20g with cutout open

PANDARESCUE said:

cutouts imo are a complete waste of time just go with a 3 inch tbe with a muffler and a cat if you have too (i dont) and also run a open dump wastegate that will work just fine no need to jank up another dsm do it right and do it once

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...but it's not a DSM

toofast82 said:

Obviously a nice 3" turboback is your best solution. Maybe not your most cost effective as you stated.

Ideally you should have your cutout as close to the turbo as you could. If you could get it placed right after the flex in the downpipe would be ideal. Placing it directly after your biggest restriction in your exhaust system, your cat, while it won't hurt, its not the best spot for it.

If you had the cutout right after the flex, then i'd say you have plenty of exhaust flow to support the 20g with cutout open

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Your posts have always been pretty solid. I agree with what you are saying. This sucker is still going to end up on the intermediate pipe though because of the $$ situation and the fact that the exhaust got screwed up at that point. I am running an E316g, so I guess the cutout in that location will still be better than the muffler. Ordered the cutout last night. I can always come back and embetter the situation if I want to.

Thanks all for your help!

Not to be a dick but it looks like you already had your mind made up before you made this thread. Of course a 3" turbo back is going to flow better than a 2.5" with a cutout AFTER the cat.

AK Maniak said:

Not to be a dick but it looks like you already had your mind made up before you made this thread. Of course a 3" turbo back is going to flow better than a 2.5" with a cutout AFTER the cat.

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No, need my car up and running and actually ordered the cutout mid-thread when there weren't as many responses. Kind of feeling iffy about my purchase but it still has to flow better than the 2.5 without a muffler. There was no "of course about it" to me or I wouldn't have wasted anyone's time asking. If I change my mind, I only lost $37. Funny thing is, I was checking into the wife's Forester XT. Even her tiny TD04 turbo is running a 3 inch turbo back SS exhaust and the cost for that is mind boggling even compared to a GVR4. Talking about $1600 for 3 inch Turbo back. The car was modded when we bought it though and didn't pay any more for the mods. Still...3 inch for a TD04 and I am talking about optimal flow for an E316g on 2.5" exhaust (granted with a cutout in not the best of places).

Just to add to this- a full 3" isn't any more expensive on a galant than on a dsm. I have a GVR4, if you have to keep your cat then use a 1g AWD DP and then a 1g AWD catback and have the catback extended the ~2" I think it was to fit like factory. Full 3" for the same price as a 1g. The downpipe is a direct bolt on, if you don't need your cat go with a 2g AWD DP as they're longer and I believe you could use an unmodified 1g awd catback then. A 3" DP can be had on ebay for $70 shipped, the only thing to look out for is eventually the flexpipe shrinking and restricting the exhaust.

And for the "not too big, not too small" debate. On a turboed car, POST turbo you want as big of an exhaust as you can get. Open o2 housing would be the most ideal flow-wise. You want zero turbulence/back pressure after the turbo. Any back pressure is BAD and should remain in the exhaust manifold PRE turbo. Will you notice gains running a 3" true exhaust on a 14b? Probably not because it doesn't flow enough air for a full 3" to become a restriction, but moving up to a 20g+ size you will.

Tyeler18 said:

Just to add to this- a full 3" isn't any more expensive on a galant than on a dsm. I have a GVR4, if you have to keep your cat then use a 1g AWD DP and then a 1g AWD catback and have the catback extended the ~2" I think it was to fit like factory. Full 3" for the same price as a 1g. The downpipe is a direct bolt on, if you don't need your cat go with a 2g AWD DP as they're longer and I believe you could use an unmodified 1g awd DP then. A 3" DP can be had on ebay for $70 shipped, the only thing to look out for is eventually the flexpipe shrinking and restricting the exhaust.

And for the "not too big, not too small" debate. On a turboed car, POST turbo you want as big of an exhaust as you can get. Open o2 housing would be the most ideal flow-wise. You want zero turbulence/back pressure after the turbo. Any back pressure is BAD and should remain in the exhaust manifold PRE turbo. Will you notice gains running a 3" true exhaust on a 14b? Probably not because it doesn't flow enough air for a full 3" to become a restriction, but moving up to a 20g+ size you will.

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This is good info, everything you have said makes sense....so what is your take on the E316g then (being that it is right down the middle of the sizes you mentioned) with the cutout just like I intend to put it down?

Also, I knew about adding the 2 inches to the exhaust which to me comes down to a hidden cost because no matter where I take it they are going to want to make tons of money for something that simple. Trust me, been there done it many times.

However, from what you are saying (not sure if I got it right). I can just run without a cat altogether by running a 2g downpipe with a 1g intermediate pipe and muffler and not have to extend anything?

This part of the post has me thrown off...

"The downpipe is a direct bolt on, if you don't need your cat go with a 2g AWD DP as they're longer and I believe you could use an unmodified 1g awd DP then."

Did you really mean use a 1g awd and 2g awd DP at the same time? Sorry if mistaken, but that is how it is coming across.

If you are confident that I can use some combination of ebay 1g/2g awd tubing to achieve the results without touching a welder, bringing it to someone, and doing this all on my back in the driveway I am all ears. I am not sure if that is what you are saying conclusively though. I have seen this sort of post on GVR4.org but it seemed to come up short by saying ".....yeah you can mix 1g/2g parts but it will still require fabrication"

Thanks for more info!

blkchr91 said:

This is good info, everything you have said makes sense....so what is your take on the E316g then (being that it is right down the middle of the sizes you mentioned) with the cutout just like I intend to put it down?

Also, I knew about adding the 2 inches to the exhaust which to me comes down to a hidden cost because no matter where I take it they are going to want to make tons of money for something that simple. Trust me, been there done it many times.

However, from what you are saying (not sure if I got it right). I can just run without a cat altogether by running a 2g downpipe with a 1g intermediate pipe and muffler and not have to extend anything?

This part of the post has me thrown off...

"The downpipe is a direct bolt on, if you don't need your cat go with a 2g AWD DP as they're longer and I believe you could use an unmodified 1g awd DP then."

Did you really mean use a 1g awd and 2g awd DP at the same time? Sorry if mistaken, but that is how it is coming across.

If you are confident that I can use some combination of ebay 1g/2g awd tubing to achieve the results without touching a welder, bringing it to someone, and doing this all on my back in the driveway I am all ears. I am not sure if that is what you are saying conclusively though. I have seen this sort of post on GVR4.org but it seemed to come up short by saying ".....yeah you can mix 1g/2g parts but it will still require fabrication"

Thanks for more info!

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Edited my post- I meant to say use a 2g AWD DP with a 1g AWD catback. Sorry about the confusion

The downpipes are a direct bolt in. If you use a 1g DP it will bolt directly to your factory cat in it's factory location, it's the 1g AWD catback that isn't quite long enough to make it to the rear.

If I remember correctly, the 2g catback is long enough that it will add on your 2" (or whatever amount it was, can't remember off the top of my head) and take up where your cat was. If I remember correctly the 2g DP paired with a 1g catback had the perfect length to run a full turboback exhaust. If it needs extended at all you could always buy a small 3" test pipe and have that bolted inbetween to give you the added length you need.

Upon further investigation (and finding your thread on the .org) you'd need 12" test pipe, not a 2". If I had a damn 2g awd downpipe I'd throw it on my galant to test fit with my 1g catback. Unfortunately all I have currently is a fwd DP which won't even come close to working.

Edit again: Pending the length of your current cat, you should* be able to bolt your cat to the 2g awd DP and use it as the extension you need to bolt to the 1g AWD catback. This would keep you SMOG legal as well as solving you issue. You may have to get creative with your catback hangers, but that really shouldn't be that hard. I've got 2 rubber hangers holding mine up just fine.