So I'm thinking of cutting my cat and muffler out and just running straight 3 1/2 inch all the way. but i have a few questions before i have at it.

Will it throw any codes in my 04.5 lly?
Will is cause a bit more smoke? (i no im not going to blow like a cole train, but will it smoke alittle more?)
Will I see any hp/torque increase/decrease?
FINALLY......HAS ANYONE ELSE DONE THIS, I am assuming it will be similar to running a straight 4 inch exhaust, but just for *****, will a 1/2 inch really make that much of a difference, vs say a 5 inch exhaust which would be a 1 1/2 inch difference?

 

I have a straight pipe, works well, no codes, no extra smoke, no real increase in hp that i noticed

will 1/2" make a HUGE difference? not really if your exhaust was a true 3 1/2", but there are soo many kinks and pinches in the stock exhaust, its only 3" in a few places, a mandrel bent straight through 4" exhaust will make a difference, but not enough to make me buy one yet

 

When I put a 4in exhaust on mine it actually cleaned up my exhaust. It dropped EGTs a little bit when DD.

 

I have a 3 1/2" straight pipe kicked out in front of my rear tire. Works just fine for me. No codes or anything.