Originally Posted by i007spectre
Im having a hard time deciding between getting just the axle back or going for the cat back, the price difference is about $300. I want better/deeper sound, but id like more power and the cat prolly gives more since it opens up more of the exhaust with bigger pipes.
I don't think you will get any noticeable power difference going from 2.25" pipe to 2.5" with this motor... especially if you car keeping the stock cats and manifolds... and then it will probably be minimal... until perhaps you add some type of FI...
There was a LOT of testing with the 4.0L V6 Mustang which had 2.25" down pipes to a Y pipe which then goes to a single 2.5" pipe for a single exhaust. Dynos showed minimal gains going from the single 2.5" pipe to 2.5" dual exhaust... so moving from dual 2.25" to dual 2.5" would most likely show the same minimal gain...