When I was doing Pro-Charger upgrades to my EFI 502, a buddy of mine (P29 SCARAB) told me about Precision Marine in Kenner La, just outside of New Orleans. I sent the Comps. there to Mr. Boos for upgrades and they worked great. That was two years ago, and no problems to date. As far as I know, Precision Marine is the only company in that area that is capable of re-mapping ECU's. (They do it for people all over the U.S.) I would suggest you give them a call, and tell them what you are planning to do. Better yet, when you are done with your upgrades, you can even take the boat there for complete mapping under real conditions while running the boat in the water. They have full dyno facilities and machine shop also. The ph.# is 504-469-7463. I hope your project turns out as good as mine.

Hope this helps
Lee

I also had Precision Marine remap my ECM's when I added a Procharger, and my setup has worked beautifully. 620 reliable HP. Blowers are definitely the most HP for the money. And they have also proven very reliable with excellent driveabililty.
Just my experience!

P29 Scarab started with efi small block 350's, then stroked, bored, changed camshaft and fuel injectors. After all those mods, including pro-chargers, Precision Marine mapped the comps and boat went from 68mph to 90.8!!! Final result was great!

Joe
Bob is right about the larger overlap reducing the compression and power band is important. Bigger is not always better here!. Remember aluminum heads will allow you more compression than iron without detonation and add horsepower better when combined with a good cam. Check with some of the good cam people and find out what grind is working best for the range you plan to boat in.
Raylar;)

Yep! That's them. Knowing how "touchy" OSO can be, I didn't want to name them and get the thread "poofed."

My motor guys (Owens Racing) and mechanics (Mars Marine) know of him from his previous life at Marine Power. I've heard nothing but great things.

I've decided to just do the 10:1 (actually 9.75:1) JE pistons and leave everything else stock, except re-mapping the computers. Owens says Prec. Marine has done this set-up before and therefore already has the mapping documented. Hopefully, I won't have to take my boat to "Lousy-ana" afterwards; but will. Thanks for the tips everyone.

Still interested in hearing if anyone's done this w/ 500 EFI's.... Keep 'em coming!