I just ordered a magnaflow universal muffler. I ordered the 2.5" si/so but im wondering if I go up to the 3" will it give me any better performance? Just wondering if it would be worth sending back to get the 3".

 

nope the 2.5" will be just fine. you wouldn't notice any difference just with a bigger inlet/outlet size. all you stock piping is 2.5" anyways.

 

Well I meant I would change everything from the cat back to 3", would that make any difference? Also is there any difference between the 14" and 18" for my truck?

 

I think the shorter the muffler the louder it will be.

 

3" is completely unnecessary for any motor pushing less than 500RWTq. If you just want a loud truck then by all means, but there is no power increase to be had from it.

 

Not unless you add a supercharger to it. Yes, 14" is louder than the 18" i have the 18" on mine and love it. 0 cab noise and highway speeds. See sig for a vid