I am building a 1989 Chevy 383 TPI + tuned port injection + engine . It has a hot roller comp cam , roller rockers , 10 to 1 compression aluminum heads and a bunch more performance parts to make at least 400 HP and 400 FT torque . With the TPI set up I will make a lot of torque down low where I will need it being a mostly off road truck . It seems like everyone wants a 1989 to 2002 6bt cummings engine with around 175HP and 450 FT torque . so here is my question why does everyone want the 1989 to 2002 6bt and not the 2003 24 valve engine and up that makes a lot more HP and torque ???????? why do they want the 1989 to 2002 6bt over the 2003 and up 24 valve engine ?????????