i,m with olds48 on this one. with the GMPP you get NEW parts plus a warranty. if you need replacement parts. lot less hassle as it is not custom made for a specific purpose. these engines are usually matched and trouble free right out of the crate(providing you know how to tune it). granted, these are mainly street/strip engines w/ the exception of the 572R. and yes, like all engines, there's always room for improvement, whether it is 275hp or 1000 hp. someone always wants more more more! :twisted: