Straight Pipe?

C-flo

Perseverance
Dec 3, 2008
74
0
0
Texas
I wanted to get some opinions on the subject of cutting off a factory muffler and leaving it straight from factory exhaust piping on a MKIII with a 7mgte in it? What are pro's and con's?
 

darryldowney

New Member
Apr 10, 2009
8
0
0
Nanaimo,BC
would you be leaving the cats in? what about the resonator/muffler thing before the last muffler? as far as i know it goes: pre-cat > cat > resonator > muffler. what are you cutting off?
 

C-flo

Perseverance
Dec 3, 2008
74
0
0
Texas
Yeah I know the resonator your talking about right after the cat, and upon looking at that I figured if I was going to cut off that far back I might as well replace all the pipe from the downpipe out, so now I'm thinking of just cutting off the last muffler to open things up a little bit but I don't want it to affect performance.
 

MA70_Powa

Boost Addict
Jun 17, 2007
180
0
0
Tasmania
if you do a straight pipe from turbo back it'll be retardely loud. A mate of mine did it with his 1jz cressida and changed his mind after 1 day :)

so dont do it.
 

TheAmazingDave

Formerly 86mister2
Feb 26, 2007
96
0
0
40
Cali South Bay
I have about as close to a straight pipe as it gets, 3" DP to 3" test pipe to 3.5" cat-back.

It's stupid loud. But with the Blitz, it sounds like sex, so I'm gonna keep it this way for a bit.
 

C-flo

Perseverance
Dec 3, 2008
74
0
0
Texas
Hmmm. With all of that being said, I will be leaving it the way it is until I get the full exhaust then. What I'm aiming for is very very loud, but also a clean sound. A "Clean Loud" I suppose is what you could say. I know cutting the muffler off will probably only offer loud w/o the clean part, but I was hoping it might help with back pressure. Turbos love back pressure right?
 

lewis15498

Don't blame ebay cheapass
Sep 28, 2008
1,397
1
0
Raynham, Massachusetts, United States
C-flo;1407639 said:
Hmmm. With all of that being said, I will be leaving it the way it is until I get the full exhaust then. What I'm aiming for is very very loud, but also a clean sound. A "Clean Loud" I suppose is what you could say. I know cutting the muffler off will probably only offer loud w/o the clean part, but I was hoping it might help with back pressure. Turbos love back pressure right?

Now your paging figgie...
 

TurboStreetCar

Formerly Nosechunks
Feb 25, 2006
2,776
3
38
Long Island, Ny
C-flo;1407639 said:
Hmmm. With all of that being said, I will be leaving it the way it is until I get the full exhaust then. What I'm aiming for is very very loud, but also a clean sound. A "Clean Loud" I suppose is what you could say. I know cutting the muffler off will probably only offer loud w/o the clean part, but I was hoping it might help with back pressure. Turbos love back pressure right?

Turbos work off of pressure ratio across the turbine. Ratio means a little here is a lot there.

A little bit of restriction in the exhaust will make a large difference in turbocharger operation. You can increase the output of your turbocharged engine a large amount by changing the stock exhaust to a more open exhaust.

The factory down pipe with cat and the turbo elbow are the largest restrictions in the factory system aside from the 2.5 inch piping.

Any restriction will cause a large decrease in efficiency of the turbocharger to turn exhaust into power. You want to fit as large/free flowing exhaust as possible to your car before hitting diminishing returns.

A full Three inch down pipe/exhaust is good for a good amount of power, start with that.
 

MA70_Powa

Boost Addict
Jun 17, 2007
180
0
0
Tasmania
Just to add to this, mine is a 3" pipe all the way from the turbo back, with only a rear muffler. Nothing else. It's not unbearably loud, but I might put a resonator on there to lower in-cabin noise a bit (can get annoying on the highway) and while driving through town it does sound quite loud with the sound echoing off the buildings, but when on the open road or while idling it sounds just fine :)
 

C-flo

Perseverance
Dec 3, 2008
74
0
0
Texas
Looks Like I'll be rolling with a 3" or 3 1/2" exhaust all the way out then. I wonder why the factory piping is only 2 1/2" anyway? I figured they would know it needs to be opened up more than that, but that was back in the 80's though.
 

Ma70.Ent

Supramania Contributor
Feb 26, 2006
1,871
1
0
NJ
C-flo;1407639 said:
Turbos love back pressure right?

Turbos do not like backpressure. N/As do not like back pressure. Nothing likes backpressure. :)

C-flo;1407848 said:
Looks Like I'll be rolling with a 3" or 3 1/2" exhaust all the way out then. I wonder why the factory piping is only 2 1/2" anyway? I figured they would know it needs to be opened up more than that, but that was back in the 80's though.

It kept the car quiet. Larger diameter = louder, etc.
 

C-flo

Perseverance
Dec 3, 2008
74
0
0
Texas
Yeah, that makes sense from a sales perspective. The only reason why I asked if turbos loved back pressure is because I had heard that somewhere and questioned it then since I didn't think that was true.
 

supradjza80

Mr. Formula SAE
Apr 24, 2007
782
0
0
38
Appleton, WI
www.uwracing.com
Well I have to disagree with a lot of people on this. I run a BIC DDP to 3.5" straight pipe on my car and really like it. I also have V band at the end to switch to a muffler and do switch back and forth on occasion. Most people really like the straight pipe sound and you can really hear the turbo through the exhaust.

Vids

http://www.youtube.com/watch?v=F747dexc_r8

but whatever, you can think its rice or gay it really doesn't matter. Its still quieter than most NA performance cars with an exhaust system when the wastegate is closed.
 

C-flo

Perseverance
Dec 3, 2008
74
0
0
Texas
yeah, but in my case I would be running factory 2.5" pipe from down pipe to cat, to resonator on out. I'm not sure what it would sound like, but my intention was to have more exhaust flowing out with less restriction.