well, to put it in simple terms the gsr is the better performing version. its set up with a better engine and i beleive it has a sportier suspension set up for better handling. which one should you get depends upon how much money you got really....the ls is going to be cheaper to come by than a gsr, and depending where you are it may be harder to find one than the other. around here (upstate ny) you'll see 25 ls's for every 1 gsr. so if ya got enough $$$ and can find one, buy a gsr if your into performance. and if you got even more money at your disposal go looking for a type r.....