STi Muffler Question

[Richard L.]

I am looking at a used STi stainless steel muffler mounted on a '99 Outback Sport. Does anyone know if this muffler would fit my '00 2.5RS coupe? Thanks.

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Richard
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[jeffg]

The STI muffler has a slightly different flange on it where it meets the midpipe. If the muffler is already intalled on an OBS then they already fixed the flange or you need to try and get the midpipe also.

In short, the muffler will fit, but you need to change that flange if you are using a stock midpipe.

Jeff

[Faraz]

I'd want a pic first because a REAL STi muffler does not come with a 4" tip or anything close its only 2.25 ....the only thing you would have to change is the midpipe.

stock 1.75" STi 2.25"

side shot vs stock

[omahasubaru]

Hmmm...

stock 1.75" STi 2.25"

Got a tape measure??
The inlet to the back box on a stock exhaust is 1.75".
The inlet to an STi version 4-6 back box exhaust is 2.25".
The tips are much larger. I haven't measured them myself, but look at your inlet and outlet. They aren't the same size. the inside diameter of the STi tip is the exact same size as the outside diameter of the stock tip (fits inside it).

If this has a midpipe you'll be fine otherwise you can get a custom one made to fit the back box's flange, not need to touch the back box inlet. SPD tuning sells/makes midpipes to fit these back boxes.. might want to contact Mike if you need help.

[AaronBBrown]

Ok...if this is a dumb question, just ignore me...

What kind of HP increase can you expect from the STi muffler? I have a WRX.

On a side note...in the WRX that compares the 330xi, A4, and WRX, they show a silver WRX driving through the rain. When they do a closeup on the tailpipe, it is clearly an STi muffler...but it's on the wrong side of the car. Did someone stick the film in upside down?!?

[omahasubaru]

What kind of HP increase can you expect from the STi muffler? I have a WRX.

Free flowing and larger exhaust does more on a turbo car than a N/A car. I have no idea the power gains for your WRX from just the pricey STi exhaust (back box only). This is however the N/A powertrain forum so I suggest you post in the Factory Turbo forum to receive better answers as that is where the question belongs.