Which is bigger restriction- Y-pipe or mufflers?

[jim1969]

I know guys have replaced both separately. Replacing which one separately gives the most gains?

[Leonardo]

DOn't know about replacing the Y alone but I have read about 10WHP for changing the mufflers alone.

 

I myself have Lachute mufflers alone. One day I'll cough up the money for the Y or replace alltogether with a japanese cat-back.

[Guest *Jedimaster*]

Muffs are heavy and heavily baffled- pretty restrictive.

[sutter2k]

I think replacing the y-pipe alone creates a new restriction right were the y-pipe narrows to mufflers.

 

The y-pipe won't make you lose horsepower, but it doesn't yield much with the new restriction you create.

 

Perrin's y-pipe is a very nice piece, but I really need cans with similiar size matings.

else the heat is not getting out of the exhaust.

I am sure this would not happen with different cans.

 

http://sutternow.com/pics/dynos/melted1.jpg

 

http://sutternow.com/pics/dynos/meltedflap2.jpg

 

In the end, they both need to go....

[TSiWRX]

Hey brother Jim.

 

I've replaced both, piecemeal.

 

Seat-of-the-pants, I couldn't feel a difference.

 

Granted, I personally think that my butt-dyno is rather well-insulated and somewhat ill-calibrated, but as I could not really feel much of a difference, it leads me to believe that the overall gains may have been, at BEST, in the 10 to 15wHP range....quite a small number for the appx. $1200 I'd spent.

 

To note, though, I have *not* obtained a re-tune since installing these components, so I do not know if significantly more can be milked out of them by some tuner-tweaking.

 

As for numbers?

 

Here's the kicker.

 

Depending on whose posts you look at, you'll see that either the cans or the Y is/are our greatest restriction(s). And what's worse, these numbers all come from pretty trustworthy sources.

 

My take?

 

"Choose the form of your destroyer."

 

It's a crap-shoot either way. Upgrade for your aural pleasure FTW!

 

And yes, I'm with brother sutter2k - in the end, both need to go if you're pursuing > "Stage II" power levels.

[Guest]

I feel like bumping this.

[FPerron]

The further you go from the turbo toward the exhause tips, the less important any restrictions will be. This is because as the exhaust gas cools moving down the pipe, it decreases in volume in proportion to the temperature drop.

[whitetiger]

I feel like bumping this.

 

Plan on getting rid of your y-pipe?

[SC GT]

I recall reading where Jon at TDC said the stock Y-pipe was actually pretty decent, and that the culprit was the muffler. He had a pic of a muffler that he had cut to show the baffles, and it made sense.

[Gire]

unfortunately for me, an aftermarket y-pipe and exhaust just won't do for my family... it'll and up too loud and I promised to not turn the GT into another Civic.

 

 

Stage two with UP and shorty DP will have to do. If I was single, I'd have the intake and exhaust all replaced in a heartbeat. It'll be much louder (ie boy-racer STi) and I'm sure with Stage two tuning, would yield at least another 30 HP out of the car, over stage two with stock intake and rear exhaust set up.

 

Am I wrong here?

[rc0032]

I cant see how can could be more than 5hp - Referance THIS its a stage 1 vs state 2 with full TBE.

[mickeyd2005]

The mufflers are definitely a restriction, but the question remains whether or not is important due to its distance from the engine.

 

I think that was answered partially by the dyno charts from PDX (same dyno and same tuner). One person had a custom TBE and MR headers and the other person had almost the same setup except with catless uppipe and stock mufflers (perrin mid and y-pipe).

 

In that comparison, both cars made almost the same power below 4200 rpm. Above 4200 rpm, the headers and mufflers made a very large difference.

 

I'm going to wait and see what kind of quiet CBE that TDC comes up with, but I'm leaning towards keeping the stock cans because the only time I drive above 5000 rpm is in 1st and 2nd gear.

[Guest]

Plan on getting rid of your y-pipe?

 

I would, if I could find catback that wasn't too loud on teh wagon.

[SC GT]

unfortunately for me, an aftermarket y-pipe and exhaust just won't do for my family... it'll and up too loud and I promised to not turn the GT into another Civic.

 

 

Stage two with UP and shorty DP will have to do. If I was single, I'd have the intake and exhaust all replaced in a heartbeat. It'll be much louder (ie boy-racer STi) and I'm sure with Stage two tuning, would yield at least another 30 HP out of the car, over stage two with stock intake and rear exhaust set up.

 

Am I wrong here?

I just slapped some straight-thru mufflers on mine. (Comptech mufflers off of ebay, which are no longer available. Probably the same as Magnaflow mufflers.) Never dyno'd, so I don't know if there is any HP difference, but they have to flow better than stock and they don't sound too loud (although they are noticeably louder than stock). Wife has never complained about the noise for close to two years.

[chenc544]

I recall reading where Jon at TDC said the stock Y-pipe was actually pretty decent, and that the culprit was the muffler. He had a pic of a muffler that he had cut to show the baffles, and it made sense.

 

Here is the thread.

http://legacygt.com/forums/showpost.php?p=364992&postcount=39

[VXCL]

there is no way the mufflers are not a restriction. i mean the exhuast flow hits a couple walls in there. but for me i cannot justify changing them becuase my car would be LOUD!!!