Stock Exhaust cut off?
 

I recently got into a accident with my 2000 Silverado and totalled it....but I bought a 2001 exactly like it besides the interior Is different, with my old truck I cut the stock muffler off between the hanger and stock muffler and I welded a L to make it come out the side, had no problems, im thinkin about doing the same but just put a turn down on the tip instead, my question is would I lose power by doing that? Or gain? I'd think I'd gain since im letting more air out, I have a cheap cold air intake for it until I get a real K&N one, this would make it a straight pipe with stock cats

You'll actually lose a little bit if you don't have any high-flow performance mods like a cam or longtubes. The stock engine needs a little bit of backpressure for proper scavenging.

Yeah I wouldn't just straight pipe it especially on basically a bone stock motor. Companies such as Magnaflow as well as others make nice straight flow thru design mufflers that flow quite a bit better than the big ole nasty stock muffler yet still provide some back pressure.

i wouldnt cut it off, and a cheap cold air is pretty much just as good as the expensive cold air