[Ron Middleton]

I think it all boils down to how up to date your ECM/Program is and how talented you are at tuning. Most of the major players such as Big Stuff, Fast, Holley, etc. are close to plug and play with minimal tuning by the end user. On GM's EFI Live and HP Tuners can tune the stock ECM as well but require much more knowledge and tuning experience. Systems like Megasquirt and others are also quite capable but require much more tuning knowledge and setup than FAST, Big Stuff, etc. Just make sure and purchase the newest version you can get, just like computers aftermarket ECM's get outdated pretty quick
(still useable but the newer stuff is almost always better). JMT.