its a stock 5.0, never changed a piece of the bottom end....i used this engine for 3 years in the states on my stang, street, track, road trips, everything, and never raced it witout NOS, used to run 75hp shot, then sent the stang back to kuwait, and for 5 years, i drove it only 10-15 times, raced it here with a 150hp shot, never had problems, guess its a strong engine....now its on my Z, we'll see next week how strong the Z is with drag radials and NOS.....