Im going to put my 2 cents in.

4G63- Still currently in production, with years of reverse engineering to back it up. Proven paths to serious performance are limited only by the thickness of your billfold.



LS2/LS7- Although assembled in Ontario, this is the pride an joy of american's everywhere (unless your a ford guy). Crazy amount of power from the factory, and good for plenty more. Great power improvement from basic bolt on's. Like the 4G, theres just a ton of aftermarket support and potential.