Something tells me this one isnt over yet

The stock 502EFI intake(which you have) will max out around 550hp. You also have MEFI 1's which are ok but not as tuneable as as MEFI's 4's
The EFI system you have is the VST system. It will pretty much all need to be replaced.
The first thing you should do is a leak down to see if the engines even need touched.
I would at most do top end rebuilds with new roller cams and ECM remaps.

The HP500 EFI intake will max out around 625hp.

If you are looking to push up the power, I suggest swap out the intake and ECM, you will be far better off down the road and cheaper in the long run...

its seems the motors have 650 hours on them and I don't know any history on them other than they run fine so I think they should come out soon.looking at options on upgrades when they do.thanks for the info

There are plenty of stock 502 EFI/MPI's with 1000 + hours that have never been touched and run just fine.

They might have 250hrs of idle time on them. A leak down test will tell you how healthy they are.

i have 540's with 500efi intakes and I agree the top out in hp at the 600-625 range . so I have had my intakes and throttle body's machined to try to gain airflow . I will know before long if it helped .

Kennyd, I know this is a somewhat old thread, did the work you had done help? What exactly did you have done?

I would like to see a back to back test on the larger throttle body. I think the factory t-body is definitely done before the intake is, but still agree with the power numbers everyone has stated. These are a couple pulls from a 9.5 to 1 comp 515, 500efi intake, stock injectors, stock throttle body, factory flame arrestor/filter. It was pulling a little over 3" of vacuum. That's definitely costing some power. [ATTACH=CONFIG]559503[/ATTACH]

I am gearing up to do a very intense dyno project using a open plenum efi intake w 2200 cfm throttle body as a baseline then switch to 500 efi intake and test each mod, going to take this intake to its very limit and try to maintain stock external appearance. I have purchased 2 500 intakes and plenums for this very purpose besides the 2 on my boat

this is what I am going to change to from my 500efi intakes , open plenum and a 2200 cfm throttlebody . going to have Boyd's engines do them