01 and 02 got the LS6 intake as well as a change in Cams as well as no EGR. 98's had larger injectors than the 99-02. 1998-1999 Had stainless steel tubular manifolds. 2000-2002 cast iron manifolds (which flowed better)
The cam change was made to increase low end torque. The early LS1 cars actually have a slightly more radical cam. Mine peaked torque at 4500 rpm, but always seemed a little soft below 3500. Gear changes to 4.11 or 4.56 remedy this.
Ram Air on the WS6/SS cars was show more than go. The exhaust make maybe a couple of HP extra on the highway. Some changes where made to the head and block castings during the Fbody production run.
SLP options could be had for exhaust and air lid, As well as all the
suspension and apperance options.
For most people mild bolt ons are enough to satisfy the HP bug, but only add a few HP, even headers on a stock motor are only worth a few HP. Heavy mods to an LS1 are usually costly, but to bring large results
Most people do not know but the 2000-2002 SS cars had a softer
suspension than the 99 and earlier cars. The older SS models had the 1LE
suspension minus the Koni DA's. 00 and up only recieved the front sway bar upgrade but the spring rates remained the same as the Z28. Older 1LE cars had the 21mm sway bar but it was determined that it was over kill and the std 19mm was on all F-body V8's after mid 90's.
The stiffer
suspension and 17" wheels do not help the SS/WS6 in the drag race dept. The best one is a stripped std Z28.
Best bang for the buck right now is an 03 or 04 Cobra, with bolt ons mid 400's, Good transmission and strong rear. They only issue I see is weight.
In the end they are all as fast as you want to spend.