Originally Posted by AmericanMuscleCars
and the 3 inch headers or tips right?
If your going the delete route and getting the res xpipe, you should be using at least 2.5" pipes out the resonated xpipe to the rear. 3" is even better and most shops will charge maybe a $30 diff for the larger pipes and you will get a deeper sound from doing this.
But with that said, don't touch the pipes between the hpipe (xpipe) and cats as its 2.5" and has to stay that. If you go higher than you'll loose power from compression loss (loss of torq).
the magnaflow 11386 is a 2.5" product but you can still accomedate 3" pipes out the back end with a simple adapter that most shops have.