anybody running a 4" dp?

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alloyguitar

it's legal, i swear...
Mar 30, 2005
570
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knoxville, tennessee
My car's in the middle of a pretty big overhaul and I just welded up a 4" downpipe off of a garrett gt4088 that is also newly installed.

My question is this: has anybody run this, and exactly how much louder is it than stock open dp?

Sounds like a stupid question, I know. And I can't start my car at the moment (since it's still in pieces) so I'm trying to figure out just how much difference one of those dynomax-style "race" mufflers is really going to make...

something like this

-Devon Goodspeed
 
A

alloyguitar

it's legal, i swear...
Mar 30, 2005
570
0
0
36
knoxville, tennessee
P.S. As you may have guessed, it's not a daily driver, and most of the places that I'd drive it don't have noise ordinances, but I don't really want to get busted at a rod run, or anything...
 
rs4rush

rs4rush

New Member
Jan 25, 2007
701
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Kirkland, Wa
Thats what i'm running (GT4088 also) and open down pipe and everywon knows your driving. Its sounds stupid under 2,000rpm's but after that it sounds cool. You will deff get pulled over, your neighbors will hate you, and everywon next to you is going to hate you. Get exhaust on there.
 
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alloyguitar

it's legal, i swear...
Mar 30, 2005
570
0
0
36
knoxville, tennessee
yeah, that's what I was worried about. Do you think that muffler would help any?

See, due to space restraints (and the fact that I don't want to bottom out every 6 inches) I was just going to run the downpipe with the muffler directly after it (parallel to the driveshaft) accompanied by a turn-down at the end, so naturally the selection of mufflers I have to choose from in such a narrow space isn't the best, let alone the fact that it's 4"

your thoughts?
 
Reign_Maker

Reign_Maker

Has cheezberger
Aug 31, 2005
5,767
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Florida
Im running a 3.5 custom turbo back, and its tucked nicely... You may be able to tuck a 4" tight, get it all the way out back... I cant wait to hear what mine sounds like...
 
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alloyguitar

it's legal, i swear...
Mar 30, 2005
570
0
0
36
knoxville, tennessee
well, my main reasoning behind 4" is because I needed a few bends in 3" to do my exhaust that I didn't have, and just happened to have a 4" downpipe from a diesel truck upgrade in my shop...

...A side note, 4" exhaust and an ssac manfold do not like to play nicely together. I have about a cm (if that) of room to cram that exhaust in there.

-Devon Goodspeed
 
Rennat

Rennat

5psi...? haha
Dec 6, 2005
2,844
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Tracy, CA
www.myspace.com
whoa... that just seems silly to do. if you did that, get a 3'' tanabe exahust if you want it to be quiet.

i heard a supra coming up to a light, looked like a 3.5 or a 4'' exhaust... and it was LOUD. im sticking to my 3''. haha
 
C

chevyeater

wastegate hose is pulled
Mar 30, 2005
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Long Island, NY
Full 4" is pretty f'ing loud. A "race" muffler and turndown under the car is going to be stupid loud. A full 4" exhaust can tuck in pretty tight on the A70 and exiting out the rear quiets it down a pretty large amount from any angle other than straight behind (driving past a cop for example will have much better chance of success). Mine has better clearance than my old 3" DP.
 
I

IJ.

Grumpy Old Man
Mar 30, 2005
38,728
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I come from a land down under
3.5" Downpipe> 3.5" Metal Cat> 3.5 to 2.5" Y pipe > twin 2.5" pipe to custom SS IJ Muffler > twin 2.5" pipes to SS can mufflers.

88Db @ 4800 rpm (legal limit here is 90Db)

Picked up some top end over a 3" system that was 97Db and makes it's power 1000 rpm earlier.

3" is hard to silence 4" is damn near impossible due to the huge internal passages.
 
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