The stock tune is pretty conservative… most bone stock M6 SS’s are putting down somewhere in the mid-360 to low 370s RWHP range. Though there aren’t many with a lot of miles, and the LS3 does open up with miles. Some LT/exhaust/cai/tune cars are over 400RWHP. With just the CAI/tune though I’d guess 380s. :shrug:
The talk about the wheels 'n slicks is that the back brakes are too big. However, I’ve seen pics and I’d be really surprised if the right 18" wouldn’t fit. And there ETStreets Radials in 18" which I’d expect to help a lot. I bet it won’t be long before somebody swaps V6 or even 4th Gen back brakes on one and runs a 15/16" rim and slicks or ET Street (non-Radials).
-TJ