Would a smaller downpipe quiet my exhaust?

[95redturboawd]

I currently have an ebay 3" turbo-back exhaust and the droning I hear while driving is getting annoying. I was wondering if I changed to say a 2.5" downpipe that would quiet it down at all? I have the tiny 1g o2 housing on my 14b so it's not like I'd be losing a lot of performance.

 

[EriClipse]

well ive read before people get a deeper sound with a larger downpipe, so it may make a difference. But you would need a fitting to put the 2.5" downpipe to the 3" exhaust.

 

[2gawdtsi]

or you could just buy a resonator, or silencer.

 

[bsbllfit7]

Do you have a cat or is it a race pipe or gutted cat. If it is a race pipe or gutted simple purchase a cat and put it in there. That should help with the droning. If that is already done go with the resonator like already stated.

 

[95redturboawd]

It has two resonators and no cat. Wouldn't putting in a cat hurt my spool time a little bit?

 

[pboglio]

A 2.5" downpipe still drones with a 3" catback. Putting a highflow 3" cat converter helps.
Running with the rear seats up and rear hatch cover helps tremendously with reducing the drone. Maybe dynamat or similar products would work as well. I run a muffler in the midpipe and it cuts the noise level down quite a bit.

 

[bsbllfit7]

also another idea besides a cat is to get a cherry bomb or whatever they are called. They are basically straight through glass packs that work as a resonator. Introducing one of these to the system would quiet it as well. This is something that turbo dodge enthusiests do with late 80's and early 90's turbocharged daytonas, lebarons and conquests.

 

[95redturboawd]

Any ideas on how adding a cat/cherry bomb will affect spool?

 

[pboglio]

Um, cherry bomb bad idea. They have louvered cores and are horribly restrictive. A good 3" aftermarket cat will not affect spool and cost about 10 h.p. on the topend at most. I could barely tell the power difference on my 2.5" highflow cat and it was just at the very very top of the rpm band. Was something like 10 h.p. restriction at 350 h.p. The bottom end actually felt better with the cat in place.

 

[99gst_racer]

You could also try welding one of these inline as a resonator: Dynomax Performance 24222 - Dynomax Race Bullet Mufflers – SummitRacing.com

It's a straight-through design, so it poses minimal restriction. I used one a few years back and it definitely quieted down the exhaust note.

 

[jag987]

A 2.5" down pipe still drones with a 3" cutback. Putting a high flow 3" cat converter helps.
Running with the rear seats up and rear hatch cover helps tremendously with reducing the drone. Maybe dynamite or similar products would work as well. I run a muffler in the mid pipe and it cuts the noise level down quite a bit.

Dyna mat is a very good product for insulation, that being said it is also a very easy way to add some weight to you car, the stuff is heavy. Makes a stereo sound great.
Also if you decide to use it, be sure not to cover you fuel pump access or any other bolts/screws that you may ever want to take out for any reason. The stuff is a pain in the butt to remove.

Also the talk of Chery bombs. I'm not a fan, but the ones I have seen don't have any baffles at all, the were a straight through design, more similar to a resonator than a true muffler. Not the best for making things quite. A good high quality free flowing muffler can quite more than the ebay ones without hurting your spool up or flow as much as say a stock muffler, but you will have to make a compromise.

 

[chico904]

You could also try welding one of these inline as a resonator: Dynomax Performance 24222 - Dynomax Race Bullet Mufflers – SummitRacing.com

It's a straight-through design, so it poses minimal restriction. I used one a few years back and it definitely quieted down the exhaust note.

I was actually looking at buying that just last night. Where did you place it in the exhaust system? I am trying to figure out if placement matters in sound difference.

 

[Ill-EagleTSi]

I have a 3" Downpipe tapering down into a stock cat back...Then about 10" past the o2 housing I installed a 3" cutout!!! Best of both worlds...I have a stock quiet car for driving and a super High flow fast spool open down pipe with the flip of a switch!

 

[pboglio]

I added a 5" diameter muffler in the middle of my exhaust pipe. It does several things, eliminates the majority of resonance, and reduces exhaust volume down further. A small resonator or cherry bomb can't do that due to the small volume. I have no problems whatsoever with noise levels. But, if you run without a cat, you will never eliminate the drone completely with 3" exhaust tubing. The rear hatch area is critical since it magnifies the droning immensely. Anything you can do in that area will produce huge sound level reduction. I don't bother since its quiet enough for me.

 

[canada4g63]

Cat isn't going to hurt you that much

 

[99gst_racer]

I was actually looking at buying that just last night. Where did you place it in the exhaust system? I am trying to figure out if placement matters in sound difference.

I had mine right about where the cat would be.

 

[johnboy1065]

I'd run a resonator, or put a cat on