Virtually any LS1 equipped T/A, with or without the WS6 package, will easily go deep in the 13's off the lot with a good driver.

I know the WS6 models look sweet, but you could save money going for a regular T/A unless you really want a WS6 car; the only major thing you will lose is the Ram Air hood, 17-inch wheels, and heavier duty suspension, otherwise there really is no difference between a regular T/A or WS6 version.

You ask about interchangeability? Yeah, I guess a lot of parts will interchange for the LS1 years from '98-'02, like the intake manifold and heads and such, but you really can't go wrong with any year you get because the basic engine is so good from the factory...no need to swap motors like you Honda guys. Just do a search and see if you can live with some of the quirks associated with owning these cars ie.) huge dash, cheap plastic, etc. I know I can.