I've raced a stock c6 and i won by a car length.

 

Well, since he has the LS2 and an auto he's at around 330-340 rwhp stock. Even with his mods he's probably only around 355 ish. I have a Z51 6 speed and it puts down 345-360 rwhp because it's a manual. There is no way, no way he's putting that sort of power down (rwhp) with the very minimal mods he's done. Now, if It's a ZO6, they are scary fast normally around 450- 460ish rwhp stock. A ZO6 with a tune is around 470-485 rwhp (depending on the state of tune).
Now, if your friend has headers, intake and a tune with an auto he's maybe around 375ish rwhp.

 

Thanks for the replies guys. Knowing the cars are so close, we're both a bit hesitant to race each other. His car is a normal C6 (not a Z06), auto/tip, exhaust (x-pipe), intake and tuned. I am sure it's even in speed with my Turbo (which is also an auto), but (claimed) dynoed at 438hp for an NA car with those mods is a bit hard to believe...