The Terminator motors have a cast iron block, forged rods and pistons. The crank is the same as all other 96-01 Cobra's, the only difference being it's balanced for the heavier forged rods. There have been problems with the pistons however (not very common though). It seems as if Ford installed them very tight in the bores to prevent cold startup piston slap normally associated with forged parts. They also come with the new for 03 heads. They have a much larger exhausr port and the tumble port intake ports first used on the 99-01 C heads. The ports have been changed to boost low end velocity and torque production. These heads are the best 4v heads other than the 00 Cobra R/Ford GT heads. The earlier version of the heads do have a problem with ticking due to a cooling problem in the #7 & #8 cylinders. They are replaced under warranty with a revised head. These heads were utilized on all the Ford 4.6 4v's for 03-04 (Marauder, Aviator, Mach 1, Cobra etc.) The motor also features an Eaton blower bolted to the heads with an intercooler underneath. There is also a reservoir tank for the intercooler and a pump to circulate the coolant. The Terminator also has a different set of cams compared to the earlier Cobras. Almost everything else is the same and everything is interchangeable (as is the case with all the modular motors). Of coure there are minor differences like injector size, fuel rails, ignition system, etc. The iron block, the blower and it's plumbing is where the extra weight of the terminator comes into play. All this results in about a 400 pound weight gain over the 96-01 Cobra's.