1. Cam Profile
2. injector size and the pressure on the fuel rail
3. Type of heads and flow rates...lift etc
4. Exhaust type
5.Compression ratio
6.Expected operating elavation
7. You can never give them enough input..but that's the beauty of efi.

You can send the ecm to OBD and they should be able to unlock the code..aka you can save the orignal bin file's make's it far easier on them http://www.obd2allinone.com/sc/toplevel.asp?cat=32

Now i am not a vendor and just sharing some thought's...These guys seem to have a great grasp on building a tune.. http://westers_garage.eidnet.org/index2.htm

Options only Good Luck..

This are what we know so far...

1. Cam Profile ???
2. injector size and the pressure on the fuel rail. Stock, we just had them rebuilt 1 was new the others had real bad spray patterns a of those 2 leaked real bad.3. Type of heads and flow rates...lift etc
4. Exhaust type. Big tube headers.
5.Compression ratio. Don't know for sure, but it is believed to be 9.0-9.5.
6.Expected operating elavation. It's EFI so I believe that not to be an issue. Like a carb. Although I don't recall a BARO sensor.
7. You can never give them enough input..but that's the beauty of efi.

We will clear up the unknown in a few weeks after the boat comes back from the river.

Thanks for the input.

My suggestion is to put a new cam in it (roller) so you know what you have. OR.... stick with the 850 Holley... You are gonna spend way more than the increases in HP is worth otherwise.

Wannabe

We will be changing the cam after vacation. The key is not max HP, but more stable reliable power, better fuel economy and stopping the over whelming smell of fuel. The 850 on the boat was not a marine carb so with sloshing fuel (even with the floats set right) it would sometime idle rough and smell like gas. Not to mention the amount of fuel the boat went through. The plugs always looked good as far as the mixture goes. This is something my friend wants to do.