I was looking at my 502 MPI Intakes and comparing the port size to the Intake ports on Dart 320 heads The area of the intake manifold port is 25 % smaller than the intake opening on the Dart Head. Does anyone modify the MPI intakes to match the cross sectional area of larger port heads? I don't mean just port matching the intake to the head but opening the entire runner to closer match the head. It looks like it could be done with a mill and some hand work around the radius where the port changes direction. Without modifying the intake I would think larger intake valves and improved flow heads (not just larger intake volume) would provide minimal gains. Can anyone confirm these conclusions. Does anyone know of shops that modify the MPI intake? Any idea on cost?

Thanks.

I have the same heads and same issue. Arizona Speed & Marine offers a reworked stock intake that has been opened up considerably and extrudo honed. It isn't cheap at $700 w/core exchange. I have to keep the stock intake because the back seat of my Nordic is very close to engine and I have a ProCharger. The side facing throttle body on the stock intake allows for a less restrictive bend radius than would be afforded by an HP500 intake. Otherwise, I would ditch it.

The amount of work you put into the intake depends on your decision to stay NA or go blown. If I were to stay NA, I would not spend the money on the stock intake and would opt for an HP500 intake or a carb intake with injector bungs.

Pm articfriends I've seen some pics. of his intake looks to have some work done to it, maybe he can help you.

I know for a fact Tyler Crockett, did an article. This had to have been late 90s. He had everything from the heads, ports to the intake. I followed this and did it on some MPIs using the Whipple Side mount, with the PIG on the back of the stock ECM. They ran pretty good, right up to the point at which he put 87 in for fuel.
I know Tylers, work on that and the increase on a MPI, for power was worth the effort.

I have two used 502 mpi intakes that I would sell one of them is still in the boat and will be removed soon. They have already been done up by Arizona speed and marine, big difference over the stock intake. With that intake and gm 088 heads with a full roller setup and a crane 731 cam and ecu tune 550hp. I'm not sure how the intake would look against the dart heads because I don't have any darts to match the intake to. Just throwing it out there. If you want more info or pics pm me. Derek