I'm putting on a 3.5" pulley, and a guy at zzp says there's no need for any other mods, but i've heard from others on different sites saying i'll need something to counter kr. Also what's the difference between a drilled thermastat and one that isn't. Thanx.

Well you could run a 3.5" but your Kr will be high but not to the point were it will kill.BUt your should do ather monds to bring your KR down. I believe a drill t-stat is so that the coolant still flowing alittle and not just to wait for the t-stat to open.

intkae and a drilles t-stat and if you can get a zzo pcm

Will just a 180 t-stat due, just to keep everything in check? Because i'm content with just the 3.5. I don't want to have to be buying this and that intake, headers whatever?

Just intake (can build it yourself), t-stat, and probably PCM.

Build it myself? Do you mean cai, because i already have a k&n open air filter. Meaning it's not boxed in, or what some might call hot air intake.

You should be OK.

GM used to warranty SLP cars that were modified with a 3.5" pulley and CAI. I don't recall the base GTX having any other mods that would compliment the 3.5" pulley. They came with a "ram air" hood, but I wouldn't call that a KR killer by any means. Maybe it was the badges?....

Oh yah, the drilled t-stat is just what D said. It allows coolant to flow ever so slightly during warm up. Theoretically this eliminates any shock to the engine by the T-stat suddenly opening and allowing fridgid coolant into an extremely hot engine. It makes for a bit longer warm up time.

The drilled Tstat is to help eliminate hot spots that develop in the head durring warm up. Hot spots can cause knock which in turn increases your KR. By allowing a small flow of fluid the "hot spots" are pretty much eliminated.