the only advantage the mildly modded r32 or r33 gtst will have over the hsv's is the weight factor.
example. 300rwk hsv would be very similiar to a 230 rwk r33 gtst.
But these days the 6.0 lt hsv's are pushing 340-360rwk modded.
Your gtst will need close to 300rwk to be on par.
Gtst's are known to have a very short 1st gear. U screw that up the Hsv's rape ya.
On an r32 gtst you'd probably need 210-220rwk for the same result.
Against a stock ls2 that should be more than enough power to own em. But alot arent stock....