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Old 02-02-2013, 12:30 AM   #1
MRF22
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Hello,

I have a 2005 STi and I will be swapping exhausts soon.
Current set up: Tomioka UEL header/up-pipe combo.
4" cat-less DP
3" TurboXS "cat" back
320whp and 330 wtq @ 16psi on Tomioka TD05 18G

I will be swapping the TurboXS cat back to an OEM STi cat back. So I will still be catless.
I will get a retune.

Questions:
1. What will it sound like?
2. Will I be able to say around 300whp and 310wtq?

Oh and I do have cobb intake, turbo inlet, and EBCS.

I'm looking for decent power but quieter for highway and city drive ability.

Thank you.
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Last edited by MRF22; 02-04-2013 at 01:42 AM.
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Old 02-02-2013, 12:36 AM   #2
Tdaz250
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Pretty sure you don't even really need to retune if your just swapping catbacks.
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Old 02-02-2013, 01:03 AM   #3
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Originally Posted by Tdaz250 View Post
Pretty sure you don't even really need to retune if your just swapping catbacks.
Really? I thought I would be running a tad rich. Which would see a drop in mpg's.
thanks for the response.
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Old 02-02-2013, 01:39 AM   #4
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No tuning is required for swapping catbacks.

It would be absurd if you even lost 5whp doing this. It adds a bit of backpressure, but not enough to make a huge difference. If you're willing to do so, dyno your car before, then after the swap, and see for yourself.
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Old 02-02-2013, 02:04 AM   #5
MRF22
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Quote:
Originally Posted by RoadKillDMD View Post
No tuning is required for swapping catbacks.

It would be absurd if you even lost 5whp doing this. It adds a bit of backpressure, but not enough to make a huge difference. If you're willing to do so, dyno your car before, then after the swap, and see for yourself.
Cool thanks. You ever heard a set up like this? I looked at a few on YouTube but they all sound tinny and high pitched. Maybe it's just bad camera.
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Old 02-02-2013, 12:12 PM   #6
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Sound is different and relative to everyone. We cannot tell you what it will sound like. I had a similar setup on my 04 YEARS ago and liked it, but others did not.

No retune is needed for a catback. There is nothing in that part that will change a single bit of your AFR. If you are worried about the power you put on a dyno, don't switch your exhaust.
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Old 02-02-2013, 01:13 PM   #7
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Originally Posted by HinshawWRX View Post
Sound is different and relative to everyone. We cannot tell you what it will sound like. I had a similar setup on my 04 YEARS ago and liked it, but others did not.

No retune is needed for a catback. There is nothing in that part that will change a single bit of your AFR. If you are worried about the power you put on a dyno, don't switch your exhaust.
I want as close to stock sound as possible.

Thank you for the info regarding the tune.
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Old 02-03-2013, 07:07 PM   #8
Tdaz250
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Lots of people run an aftermarket down pipe with the stock catback. I personally like to hear mine, i have invidia n1 and catless dp.
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Old 02-03-2013, 07:59 PM   #9
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It will increase the back pressure, you will gain some spool up time. If your tune is pushed to the limit spark wise (practically no sube tune is, which is a shame) at least log it for a while to make sure the added back pressure hasnt lowered you knock limit.
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Old 02-03-2013, 10:29 PM   #10
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It will increase the back pressure, you will gain some spool up time. If your tune is pushed to the limit spark wise (practically no sube tune is, which is a shame) at least log it for a while to make sure the added back pressure hasnt lowered you knock limit.
Ok cool. I will probably get a tune later down the road but as long as I can commute.
Main concern is it being quiet. Lol
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Old 02-03-2013, 11:18 PM   #11
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I wouldnt worry about it too much. With how most subarus are tuned you wont notice anything beside sit being quieter.
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Old 02-04-2013, 01:12 AM   #12
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It's going to sound like crap!! I did it, worst raspy crap ever.
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Old 02-04-2013, 01:21 AM   #13
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It's going to sound like crap!! I did it, worst raspy crap ever.
Really!? Dang. That's what I was worried about.
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Old 02-04-2013, 01:21 AM   #14
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It's going to sound like crap!! I did it, worst raspy crap ever.
What was your set up?
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Old 02-04-2013, 01:31 AM   #15
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What was your set up?
Durr! OEM CBE, catless dp.

OEM mufflers have no glass packs. It's just chambers of raspy air blowing around back there. Don't do it unless its with OEM dp.
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Old 02-04-2013, 01:42 AM   #16
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Quote:
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Durr! OEM CBE, catless dp.

OEM mufflers have no glass packs. It's just chambers of raspy air blowing around back there. Don't do it unless its with OEM dp.
So do you think putting a resonator on my current exhaust would quiet it down?
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Old 02-04-2013, 02:00 PM   #17
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So do you think putting a resonator on my current exhaust would quiet it down?
Yeah it would, hard to say if it will quiet it down ENOUGH for you though
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Old 02-04-2013, 02:12 PM   #18
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Yeah it would, hard to say if it will quiet it down ENOUGH for you though
Cool thanks! I'm gonna do a resonator and if that's not quiet enough then ill put in the stock axle back.
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Old 02-04-2013, 02:22 PM   #19
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So do you think putting a resonator on my current exhaust would quiet it down?
Quite? No, zero. Change the sound? Yes a little.
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Old 02-04-2013, 02:23 PM   #20
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Cool thanks! I'm gonna do a resonator and if that's not quiet enough then ill put in the stock axle back.
2.25" mated to 3" isn't going to really work.
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Old 02-04-2013, 02:34 PM   #21
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Quote:
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It's going to sound like crap!! I did it, worst raspy crap ever.
I haven't tried it catless, but my catted DP into stock catback on my '12 sounds almost exactly like stock. It's just a hair more aggressive sounding than stock, but barely noticeable.
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Old 02-04-2013, 02:47 PM   #22
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2.25" mated to 3" isn't going to really work.
Ya it will work. It's 2.5" and I will be using the Grimmspeed adapter to mate it up.
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