Exhuast Dilemma

[Saturdee]

I plan on buying a full Megan Racing exhaust system in the near future. I planned on getting a 2.5 downpipe, test pipe, and 3 inch catback. I wanted the 2.5 downpipe because I heard it helps prevent boost creep. But anyways, my question is about the test pipe, I know it has a 2.25 inlet/outlet, but will it fit up fine with the 3 inch catback and the 2.5 inch downpipe? And if it does fit fine, wouldn't the 2.25 size inlet/outlet just make the flow worse?

 

[9!'clipseDOHC]

You don't want to go from 2.5" to 2.25" to 3". Either get a 2.5" or a 3" test pipe.

 

[Colt4G63 also]

I plan on buying a full Megan Racing exhaust system in the near future. I planned on getting a 2.5 downpipe, test pipe, and 3 inch catback. I wanted the 2.5 downpipe because I heard it helps prevent boost creep. But anyways, my question is about the test pipe, I know it has a 2.25 inlet/outlet, but will it fit up fine with the 3 inch catback and the 2.5 inch downpipe? And if it does fit fine, wouldn't the 2.25 size inlet/outlet just make the flow worse?

Yeah that's a restriction. Go with 3" from the turbo to the bumper.

 

[-TunedDSM-]

I believe the Megan Racing downpipes are cat eliminators, so you shouldn't need a test pipe. I'm not 100% for the FWD's, but my 2g AWD downpipe and catback bolted right up together without a test pipe. You may want to contact a vendor or Megan Racing directly to check.

 

[wkmitsu]

Don't bother getting a 3" system with a 2.5" downpipe. As everyone has said, just go 3" all the way back. And yeah the Megan downpipe eliminates the cat, so you don't need a test pipe. The 3" downpipe will mate up to the stock O2 housing too, so you shouldn't have any problems there.

 

[Saturdee]

Alright I'll do the 3 inch setup, but should I worry about boost creep?

 

[paultheninja]

Port the wastegate flapper or get an atmospheric o2 dump pie. Should control it if you have creep

 

[boostforfun]

Yes, it will creep like crazy. We just did a 7cm housing/ e3 o2 housing, 3" turbo back and it creeps really bad now.It went from 11psi to 18ish till redline now. The TRUE 3" downpipe that doesn't bell down at the o2 doesn't' fit the stock o2 housing very well, either. It might work, but seems pointless considering the restriction of the factory o2.

Just my .02.

 

[9!'clipseDOHC]

The TRUE 3" downpipe that doesn't bell down at the o2 doesn't' fit the stock o2 housing very well, either. It might work, but seems pointless considering the restriction of the factory o2.

Just my .02.

The Megan Racing downpipe isn't a "TRUE" 3" dp. It necks down to 2.5" at the o2 housing.

A 3" exhaust will cause creep but a ported stock o2 housing or a tubular housing or an atmospheric dump, will all help with that.

My 3" system is creeping past 5k RPMs. I just ordered the Megan Racing recirculated tubular o2 housing. Once I get it on I'll let you know if it cures my problem. It should though.

Hope this helps!

 

[boostforfun]

We are running a ported e3 o2 housing and it creeps really bad, so i'm not sure how much I buy that. We even ported the wastegate hole and approach on the turbine housing.

Not trying to convince him not to run it, just giving him real world info from something i did just last week on an otherwise stock 1g fwd.

 

[9!'clipseDOHC]

We are running a ported e3 o2 housing and it creeps really bad, so i'm not sure how much I buy that. We even ported the wastegate hole and approach on the turbine housing.

Not trying to convince him not to run it, just giving him real world info from something i did just last week on an otherwise stock 1g fwd.

Well I'm still on a stock 2g housing so I can't give him my experience yet. That's why I said I would let him know after i get the tubular housing on. But from what I have heard and read, that should take care of it.

boostforfun, what turbo are you on? (I just looked at your profile and it says E316g, those are bad creeping turbos to begin with) OP what turbo are you on? I'm running a stock 14b. Currently with the unported 2g o2 housing and full 3" exhaust I hold 14 psi until 5k RPMs and then it starts creeping up to 20 psi. I will let you know how much the tubular housing helps as soon as I get it on.

 

[GsXdSmKingGsX]

Ok one of my buddies runs a 3" turbo back and he hasnt experienced boost creep at all. He ran it on his T25 and when he upgraded to a e316g

 

[paultheninja]

14b,16g,18g, and 20g are all known for creeping. Ported waste gate flapper should cure all problems. I run just an open dump tube and cures all problems for my 16g

 

[Saturdee]

So do you guys think that since the Megan downpipe's inlet is 2.5 it would prevent boost creep?

Originally I wanted to go with the 2.5 downpipe because I heard you wouldn't get boost creep with that, and just run a 3" catback, but I just don't know if the flanges would match up from the smaller downpipe to the larger catback.

 

[paultheninja]

They should match up. When your putting your exhaust on have your waste gate flapper ported and o2 housing done and you shouldn't have to worry about creep.

 

[joescool2008]

I have a 3inch megan racing exhaust on my 90 gsx and it's great, it starts out with 2.5" to match the o2 flange and is 3" all the way through. I've owned it for about 2 years now and it still polishes up like new and sounds great still. It caused my 14b to boost creep due to a crappy internal wastegate but when you upgrade like that theres other things to get as well. Another bonus is it has all the stock hanger locations .

 

[Saturdee]

Alright, so what you guys think I should do is just go with the 3 inch setup and just port the wastegate flapper and o2 housing? The only thing about that is I don't have the tools to port them myself

 

[91gsxnoob]

Alright, so what you guys think I should do is just go with the 3 inch setup and just port the wastegate flapper and o2 housing? The only thing about that is I don't have the tools to port them myself

Harbor freight has their version of a dremel for around $15-20 depending if it's on sale. You will use it quite a bit once you have one, at least I have. Just go with the 3" and port it, if it still creeps port some more, if it cracks then get an atmospheric dumpadity dump.

 

[boostforfun]

Sorry about the late reply, I have been out all day. The car I am speaking of is not mine, but a friends. Its a bone stock 14b car other than what I mentioned.

And just to be clear, I am unsure what an atmospheric dump would do to solve creep. I would like to see some mentions of real world people that have experienced any benefit beyond sound from an atmospheric dump o2.

 

[Saturdee]

Yeah I guess I could do that, it would save money down the road for me anyway. My car is pretty much bone stock, so my plan was to just use a 2.5 downpipe temporarily until I get a evo III 16g, then go with a 3 inch downpipe, but it wouldn't be a bad idea to just buy the 3" downpipe now and save the money from buying a new one in the future and still having to port it anyways.