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Discussion Starter · #1 ·
Shiv just did a dyno session w/ a car that had a uppipe/downpipe/ion turbo and a stock back box (I think he was after the "stealth" look). He was having a tough time tuning it and came to the conclusion it was the oe back box giving him trouble, sure enough removing the muffler section made 20hp and a good tune!

Other tuners have found similar results. While a hi-flow muffler will only add a couple of horsepower w/ a stock setup, that same muffler will add 10-15 hp w/ a high flowing setup.

Big Sky
 

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Discussion Starter · #3 ·
Thanks for linking the thread. The other thing I thought was as important (maybe more) was the mention of the boost misbehaving badly (oscillating) w/ the oe back box.

Big Sky
 

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There was mention of some kind of exhaust wave resonating back up the pipe, causing all sorts of inconsistancies.
 

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Discussion Starter · #7 ·
Xonya said:
So if you ran straight pipe, no exhaust you would see a 15 hp gain ?
You would see at least that gain (ofcourse w/ a free flowing exhaust-including uppipe) over the stock setup only. It would be a gain over a high flow catback, but quite a bit less. You've probably seen some vehicles running the supertrap setup- has several removable discs- remove them all for max power, put some in so you don't get arrested;) .

Big Sky
 

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Here's the dyno chart from the above thread as posted by "100":

I noticed this thread a couple of days ago. What's also interesting is how the gains only appear after 5000 RPMs, and not across the rev range. But that's a very significant gain after 5000! It makes me wonder though if keeping the stock exhaust would help with the turbo's longevity.
 

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Big Sky WRX said:
You would see at least that gain (ofcourse w/ a free flowing exhaust-including uppipe) over the stock setup only. It would be a gain over a high flow catback, but quite a bit less. You've probably seen some vehicles running the supertrap setup- has several removable discs- remove them all for max power, put some in so you don't get arrested;) .

Big Sky


Whats supertraps :confused: ?
 

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Back form the Dead!!!

So I'm thinking of going catless in a couple of weeks (sti up-pipe/ stromung bellmouth DP) but I think with the Stromung dual tip cat-back, I'm gonna be super loud. Should I put the third cat back in, or swap out the muffler section?Big sky points out some turbulence issues, which make me lean towards re-installing the 3rd cat, but I thought I'd look for some input and opinions, or what you would do.....thanks
 

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Those of you who are currently running the stealth back on the stock turbo should not fret. The part of this test that made the results so startling was the ION turbo. Sure its a remanufactured stocker, but its output surpasses that of the stock turbo. I don' t think that any one ever advocated running the stock muffler on a WRX with an aftermarket turbo.

The same phenomia is observable in the fact that most people who purchase a system from us with a cat, end up coming back to us after they have upgraded their turbo to get a race pipe. The reason? Restriction is a much bigger factor on engines with increased output. Although the high flow cat is only stealing 5-8hp on a stock WRX, on a WRX with an aftermarket turbo it is responsible for approximately twice that.

Food for thought.

Cheers,
 

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Discussion Starter · #15 ·
redwag said:
Back form the Dead!!!

So I'm thinking of going catless in a couple of weeks (sti up-pipe/ stromung bellmouth DP) but I think with the Stromung dual tip cat-back, I'm gonna be super loud. Should I put the third cat back in, or swap out the muffler section?Big sky points out some turbulence issues, which make me lean towards re-installing the 3rd cat, but I thought I'd look for some input and opinions, or what you would do.....thanks
Run it for awhile, if its too loud put the resonator section back (rear midpipe), if it's still too loud try the oe third cat- it's not very restrictive.

Is Stromung making a bellmouth downpipe now? If so, good for them.

Big Sky
 

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allright guys, i have the same delema, i live in a small town and i've allready gotten 2 equiptment violations b/c my exhost is too loud b/c i have no cats... i was looking at that muffler site but it still seems too loud... is there any other muffler that anyone could suggest... my only concern is the back pressure on the turbo... is that bad for the turbo? and if i do put the stock muffler back on am i gonna have problems? thanx
 

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Discussion Starter · #18 ·
I'll make the same suggestion- try the putting back in the front mid section (3rd oe cat) and the rear mid section (resonator), it will quiet things down w/ very little performance penalty.

The oe muffler won't hurt anything, but power- probably 10-15 hp!

How do they know it's too loud- do they have a decibel meter?

Big Sky
 

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sky,

are you running the TXS highflow cat or a racepipe?
 

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race pipe i guess, that means no cat's right?.... an they don't have a decible reader but again i live in a small town so if i take him to court he's just gonna bust my balls untill i can get outa this godforsaken town... thanx for the suggestion though.... i guess a 10-15 hp cut won't hurt that much... ohwell
thanx again

oh ya is2scooby does that thing really work?! if so damn, thats what im gonna get
 
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