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Resonated Test Pipe

1K views 8 replies 5 participants last post by  Geo 
#1 ·
A search turned up precious little about resonated test pipes, other than the fact that at least a couple guys use them (rabidonkeyboy, augmach).

My question is this: do they limit flow much vs. a straight-through test pipe? And how much quieter are they? Looks like I can get a 3" resonated test pipe from testpipe.com until I can get a N1 downpipe or whatever installed later. But even then, I might just look for a way to keep the resonated test pipe if I like it a lot even with a new downpipe. Is that possible?

J Doug
 
#2 ·
just get a regular test pipe...its not really much louder at all imo. my 2.5 turbo back w/test gives it a mean throaty tone that sounds badass and not whiny and buzz like .... you know like a honda. three inchers sound even meaner. just make sure that you do some research into whether you want to construct a 3 or 2.5 in exhaust. i personally would get a test pipe if the law is not a concern. you could even bolt a cat shell around the piping to fool people if they do look (which they wont if you have a sticker)
 
#3 ·
I'm planning on the Greddy Evo exhaust which is 3", plus I'm moving to Florida this summer (no emissions testing- woo hoo!) so I don't have to worry about the eco-police. I was just worried that a 3" exhaust with straight-through test pipe would be annoyingly loud. And yes, there have been lots of threads about exhaust sound...

J Doug
 
#4 ·
No it is not much louder than a 2.5" with test pipe I had an ahp Test pipe and cat back for my car. My buddy just bought a muffler shop I have almost unlimited usage of shop, tools, and pipe. I know have 3" on the car with a straight thru muffler and 4" dtm tip. The 3" starts at the Flex pipe on the down pipe. Made a big difference on spool up but I lost some low end punch. If you do a resonanated test pipe I will act as a muffler and decrease flow unless it has a drilled core. Most of the resonators I have seen are louverd(sp?) You can regain flow by installing it backwards so that the air flow is not caught by the louvers. But if you do that you shoulp just by a full pipe insted of the resonator. My oppion and not your's
 
#5 ·
Yea i was wondering how much hp/flow i would gain by just going to the n-1 full downpipe and eliminating my resonated test pipe,I think it sounds awesome now,but would like to find out how much louder it would be with 3 inch dp instead of a 2.5 dp.
 
#6 ·
I couldn't say how much or what the sound increase is. I went from factory down pipe and test pipe back @ 2.5 with a straight thru muffler with a 4 inch rolled edge pencil tip to almost a full 3 inch from the turbo back. Sound increase not to bad cruising a around but at idle and under a load huge increase not loud but deep. I originally had a Muffler shop flow master and it sounded like crap. I had to prove a point to a buddy of mine. It pays to have a freind that owns a muffler shop. do the after market 3" exhausts go over or under the cross member? My 2.5 from Ahp that is now sitting in the shed along with the factory exhaust.
 
#7 ·
Geo said:
If you do a resonated test pipe it will act as a muffler and decrease flow unless it has a drilled core. Most of the resonators I have seen are louverd(sp?)
What do you mean by a "drilled core" and how do I tell if a test pipe has one?

J Doug
 
#9 ·
doug said:


What do you mean by a "drilled core" and how do I tell if a test pipe has one?

J Doug
Sorry I was talking about the mentioned resonated test pipe. If you find a drilled core resonated test pipe basically an old school cherry bomb or glass pack. Sorry V8 days. This is how I understand the resonator. Louverd decrease in exhaust flow and velocity also decrease in sound mounted the right way. Mounted backwards you gain flow but do not reduce the exhaust sound much. Drilled core is basiclly a pipe very little restriction if any minamul(Sp?) reduction in exhaust sound. Both will change the exhaust note which could also be done without the added expense of the resonator. Best way is to use a plain old exhaust pipe for the resonator. I have some pictures for my old probe site if you want to see inside a louvered resonator and a drilled core muffler here is the link http://members.tripod.com/turbo93pgt/id34.htm
 
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