My engine is a completley stock internal 5.0 of 1995. The only thing that is fixing to change in the fuel injectors, (i want more power) When i bought the car it was at 8psi and ran great with the stock injectors and internals. I also have a CAI, Short throw, Exhuast, and 3.73 gears. If you just want a fun and easy to put on blower get the KB. Everytime i go WOT the rear tires break loose. i love it. its like having a big block undder the hood. Its rather exspensive. $3K but in my opinion its worth it for the power, and the whistle when i drive.