so i got a pretty good deal, and recently picked up a universal megan racing muffler..my question is what should i do..piping wise..2.5" from the axel back or cat back? or just weld it to the stock pipes good enough? prolly not

 

What do you plan on doing down the road? If you plan on doing 2.5' front to back I would say do it to the cat or even more. You aren't going to gain a lot of horse power since the rest of the exhaust is 1.5, Just think, your only as strong and your weakest part! but you should get some good noise!!