Stage 2's don't really come in "kits" per se. It's just a downpipe, a cat-back, sometimes an intake, and either a professional tune, or a Cobb AccessPort with an e-tune or an off-the-shelf (OTS) map from the Cobb website.
So the question then becomes, who makes the best quality hardware and who are the best tuners.
Hardware: there is no right answer (except for avoid Agency Power. For the love of all that is holy, avoid them at all costs). Search the multitude of threads discussing exhausts/intakes etc. and find one you like the sound of. Start here:
http://forums.nasioc.com/forums/show....php?t=2119289
Tuners: Hit up your local chapter and ask around, read some reviews, make a decision on whether you want a pro/e-tune/OTS, and then take the plunge.
Also, as Unabomber conveniently advertises below his name, fire him a PM with the picture of a hot male police officer or fireman and a list of what you've decided on buying to see if he can do you any favors on price.