LS4 Performance - Quick Exhaust Question

Grand prixs; does the 3.8 catback systems work on the 5.3? I seem to remember the answer being yes, but a hanger has to be added?

From what I've heard yes. But the piping will be 2.5 at the largest. I would go with custom 3inch

Well routing would be very similar. I bet the only problem would be mating up to the stock cat or down pipe. It's possible you would have to weld them together or an adapter

a 3.8 exhaust system has the same routing HOWEVER the piping goes from 2.5" to 2.25" at the Y, i was wanting to upgrade to GXP exhaust on my GTP just because its bigger then the oem piping, yes there is a hanger position change difference between the systems as well, its worth it to swap if your putting the 5.3 catback on the 3.8, but not visa-versa

If you're looking at buying some catback to the muffler piping I'll be selling mine as soon as I get my headers. I'm switching to 3" exhaust and currently have the magnaflow catback system which is 2.5" all the way I believe.