HughB

Hi all,

Just was curious on what kind of gains would I get with replacing the stock mufflers with a set of Borla Pro XS. My last ISF had straight pipes and I hated the loudness and drone. The setup i have now with the Borlas have almost the perfect sound I was looking for. A nice deep hum. I wanted to do an axel back setup but the exhaust shop guy said that it won't make much of a difference with the crush Y bend.

I'm also looking to get a set of PPE catless headers but wanted to keep the stock piping and resonator. My goal is to keep that nice deep hum but I also want some power gains. Thanks again for the input!

rmillsISF

I just went through this and here's my recommendation.

1. If you're getting headers, get a QUIET exhaust because it WILL BE loud afterward.
2. With the mufflers, get the shortest you can. I went with the Magnaflow 12226 and would probably go with the round 5" if I did it again due to the fitment. It's a tight fit end to end down there as well.
3. I kept the resonator and mid pipe as it's already 2.5" and rebuilt behind that.
4. The Y pipe needs to go. REdo the muffler from the flange back or there's a lot of restriction. Get a 2.5" Y and rebuild it all. it's not that much more work.


Listen to these with a good speaker system on your computer.
With JUST the mufflers swapped. 2.5" y pipe:

With PPE Headers and the same exhaust setup:

idoke1

iTrader: (5)

I have the borla pro xs mufflers right now on my F and I love it. It's definitely on the quieter side of mufflers and it flows very good. I remember reading an article where they tested many types of mufflers to see which one flows better. The borla had the best flow rate.

Vervish

iTrader: (4)

I do not think you will gain much if any power. The biggest restrictions on the stock exhaust are the Y and the cats. Just replacing the muffler on an otherwise stock exhaust will get you nicer sound - but not much power.

HughB

Thanks! It was your original thread earlier that made me decide on that setup. I was going with the Magna but due to time and circumstances the Borla was the closest thing they had to it. Love the sound! I didn't know the Y bend was so restrictive, good to know

Are you full cat less in your set up? Any issues with the CEL?

Thanks for reply all!

mindcrime

iTrader: (2)

what size y pipe?

Justin727

If $ was no issue I would suggest of course the PPE headers and their Dual Mode exhaust system. Quiet when you need, beast when you want.

FinLIFE

iTrader: (8)

^thats why im considering the xforce varex exhaust. Adjustable exhaust tone.

rmillsISF

I went with the 2.5 to dual 2.5" Y pipe. I have the stock mid-pipe with the cat. I just removed the pre-cats in the headers when I did the PPE headers. The PPE comes with the simulators and gaskets and all you need to eliminate any CEL