i honestly have no idea...there has to be something changed more than just the type of aspiration. my guess is that the carbed model uses a "better" intake manifold. SO many people who build the modern dodge V8s (such as in the trucks) are quick to buy the mopar M1 intake manifold, but it is single plane, and single plane manifolds provide more advantage at high rpm. i ran a single plane manifold on the mirada for a very short time, and it killed the bottom end. we purchased an intake for amandas truck, but they only seem to make them with MPFI in single plane, and i didnt want to take anything off of the bottom end, and in the 5.9 magnum, the engine is virtually worthless above 6 grand, so the single plane intakes help it breathe better on the top end, but im sure that it hurts the bottom. which is why i sold her intake. however, they do make an M1 in dual plane, but you have to convert the truck to a carb system.

i do know this, though. i have spent alot of time at the drag strip, and aside from new cars, i see VERY few cars with fuel injection. i have always assumed that it is because the FI systems require alot more work with the need for sensors and a control computer, but evidently the carbs have some sort of performance advantage, but they are far more tempetmental. i would think that with throttle body injection (which is little more than a computerized carb) wouldnt differ that much with the exception of the eletronics. i know someone who has a 9 second chevelle SS, and when he went to the "cool new fuel injection system" the nightmares began...lots of tuning issues, etc.