Does anyone know what length headers (long tube, short) would fit on an 2008 5.3 with stock cats?

 

Shorties will but u can get long tubes with a catted y pipe

 

Don't even waste your time on shorties, go long tubes.

 

+1. When I put long tubes on my truck I couldn't feel the power increase by much so I wouldn't even waste your money on shorties (basically whats on the truck stock). If you haven't had your truck tuned I would do that first though. More bang for the buck

 

So then if I run long tube headers I would need to make my own y-pipe to meet the magnaflow exhaust?

 

I had a muffler shop make me one but I didn't put the cats back on. They ran a 3" exhaust off the passenger side header and just brought the driver side over and tied directly into it. I'm not sure if any company makes a premade Y pipe for cats though. I would honestly delete them if your state doesn't have emission tests.

 

No all the header's have y pipes with them.. Take a look at some of the sponsors to the right for pricing.. IMO id go with American Racing