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Old 05-14-2019, 07:59 PM   #1
user15
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Default Stock cat back exhaust limit's

Been doing some reading around and while the great sti/WRX mufflers situation remains a mystery I'm wondering how much power can the stock cat back exhaust handle before it needs a 3"? Seems like power gain is minimal and noise is the biggest gain. I'm looking to stay as stock looking as possible.
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Old 05-14-2019, 09:02 PM   #2
tegxsi
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IMO, usually stock catback is fine with a stock turbo... You'll help the turbo be a bit more efficient and unlock a few ponies with a larger diameter piping but not much.
J-pipes are already 3" so some prefer to have it 3" all the way and not have a neck-down.
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Old 05-14-2019, 09:23 PM   #3
user15
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My plan is headers, j pipe and sti mid pipe and muffers to keep it quiet
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Old 05-15-2019, 08:47 AM   #4
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I have a resonated j-pipe (catless) and the Invidia Q300 single exit catback. 3" from turbo back, and since the exhaust is resonated (the stock WRX exhaust is not), it is actually as quiet as stock - if not a little quieter - under normal conditions. Opens up when you get on it, so has a better sound under hard acceleration.

If you are looking for quieter, but free flowing, I would recommend that. If you want the double look, they make a double model in the Q300 as well. I just prefer the single look and it is lighter (not too mention it is a 4-cylinder, not a 6 or 8 with the cylinder banks going out of different pipes).
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Old 05-15-2019, 09:35 AM   #5
Schoat333
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I have the Cobb catted Jpipe with stock catback. I love the sound, so I am hesitant to change it. I feel like all of hte aftermarket catbacks loose some of the good tones that the stock exhaust has.
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Old 05-15-2019, 01:43 PM   #6
CGumina
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When I went from a stock exhaust to a Q300 catback, I was effing floored with how much quieter it was inside the car. Less "boomy" and way healthier sounding outside the car.

If you want quiet, stick with the factory J-pipe and a polished-tip Q300 exhaust. Until you get a bigger turbocharger, you'll be just fine with those parts for a long time.
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Old 05-15-2019, 01:59 PM   #7
slimFA20
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If you want the most quiet exhaust, that would be HKS Legamax catback. btw I had the Legamax and currently have the q300 (w/ cobb j pipe non res). Legamax makes stock exhaust sound loud.
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Old 05-15-2019, 02:14 PM   #8
CGumina
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Quote:
Originally Posted by slimFA20 View Post
If you want the most quiet exhaust, that would be HKS Legamax catback. btw I had the Legamax and currently have the q300 (w/ cobb j pipe non res). Legamax makes stock exhaust sound loud.
Seriously- could you post a video of it?

I'm considering making the switch to a Legamax with a Cobb J-pipe with a cat and a resonator, and I want to get an idea of what I'm shooting for.
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Old 05-15-2019, 02:53 PM   #9
slimFA20
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Sorry I don't have a video. If you look on subispeeds site, they have a vid from HKS. I actually sold the exhaust after 2 months because the car was TOO quiet (while inside the car) you won't even hear anything but noise coming from the engine area.
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Old 05-15-2019, 03:39 PM   #10
user15
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I should have said I want my car to look stock from the outside. I'm actually tempted to have a local shop make me a 3" to the Y then down to 1.5 or 2" to the stock mufflers/
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Old 05-15-2019, 04:49 PM   #11
Craigster08
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I ran a Cobb catted J-pipe non-resonated with stock cat-back for about a year and half. Finally decided to finish off the rest of my exhaust, and there was no noticeable difference outside of noise. Which you've already stated.

I went with a Borla cat-back which is 3 inches to the Y, and tapers down to 2.25 inches I think. Mufflers are smaller compared to stock. It's a nice sounding exhaust.
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