Originally Posted by
YoungPerformance
The problem you will run into is the intake. That manifold will severly limit your power potential. There are quite a few things that can be done to the intake to help it flow. However, personally, I think it is a waste when it can be replaced pretty reasonably. You can extrude hone the intake (about 800-$1000), bore out the throttle body(200-300), shorten the runners(100-200), and do some hand blending (200-300). These things will drastically help the manifold. However, even with all of that, I have never been able to make much over 600 hp......ever. At some point you will need injectors. The problem is there are no drop in injectors that will fit that manifold. I modify, drill, cut, weld, mill,etc. the fuel rails and manifold to make a Mototron injector fit. It turns out great, but it is a bunch of work. So...... now we have over $2000 tied up in a so-so manifold. For about $2500-$2600, you can replace it with Holley's setup. I buy there manifold setup without the electronics and use a Mefi. To answer your other question, no problem to reprogram the ecm. I order them with the manifold, 2000 cfm throttle body, fuel rails, injectors, croosover tubes, IAC, TPS, ECT (coolant temp), Map sensor, IAT (intake air temp). It is a dynamite setup that can make as much power naturally aspirated as you would like. I have made over 800 hp with one. Without doing the above work to the MPI intake, I don't think you will see 550 hp, even with a 540.
If you were to get the Holley intake setup, then you could just bore the engine to 516 or 525 and skip the 540. This will save you a ton on money since you can reuse the crank, balancer, flywheel, rods, etc. Just replace the pistons. I would bump the compression to 9.3 for premium, or 9:1 for 89 octane. If you did a little cleanup in the heads, you could make over 550 hp without even trying. With a set of aluminum heads, you could make well over 600 hp.
This is the route that I take on the majority of 502 MPI's that I see. Once I explain it in dollars and cents, most see that the Holley setup is the way to go. Let me know if you have any questions or if I can help in any way. Good luck.
Eddie