Ah yes, the voice of reason, from the man of experience. Thanks, Rich!
The fact is, modified cars are NOT STOCK and, for all intents and purposes, the systems that are modified have NO WARRANTY. Yes, a good shop will give you something more than the traditional "5 feet or 5 seconds" IF there is infant mortality. Once you run it for a couple thousand miles, it's yours. The warranty that Rich quotes above is from one of the most respected and most expensive shops in the country. Yes, you get a warranty...and about a 25% premium on the bill. It may well be worth it, but the point is the warranty isn't "free".
As to the GM warranty. yes, there is Magnuson-Moss, but dealers have wide discretion in practice and if the guy doesn't want to fix your car, you'll play heck getting it fixed there. Lawyers or no.
Ray, the question you have to ask yourself is, are you prepared to deal with the potential crap of a modified car? Up to and including buying your own new engine if you have a catastrophic failure due to GM/aftermarket/your shop/fate/whatever? Are you willing to take it back to the shop 3 or 4 times to get it right? Are you willing to go through 3 tuners? Etc, etc. That's not to say that these horrible things WILL happen, as they probably won't. But they might and if they do, and your car is modded, you're on your own. Would that be just painful, or catastrophic? If the latter, leave it alone.
On the other hand, if you're willing to take a deep breath and start down the hot rod path, then the questions become much simpler. Indeed, there's only one question: speed costs money, how fast can you afford to go?
That's a smart-ass way of saying "set a budget and the rest comes from that". Decide on a dollar amount (more than stock), and a "hassle factor" (driveability, reliability, mileage, etc., all worse than stock) and then you can make a realistic plan and get useful advice on what might be an appropriate package for you. I wouldn't just throw parts at the car because "this is what everybody does". I see more useless crap at Vette shows than I can believe.