Hi-Lo Injection absolutely, categorically DOES NOT WORK with M800 OEM ecu's. I have confirmed this myslef on the bench and in the car...the firmware in the m800oem is specific to the OEM ecu range....it will allow more than 4 injectors, but will not allow Hi-Lo to be enabled....in fact gives you error message along the lines of "M800 OEM cannot have Hi-Lo enabled... (you would have to be careful of the track sizes, that they are suitable for injector current...most of the inj5-8 in the OEM are used for other functions, including via some interfacing components on the daughterboard...if you have to ask how to get around this, it's not for you!
Have checked this exact fact with Mark and Jamie, and it is sadly exactly as described. You can check for yourself...build a normal M800 4 cyl cal offline, enable the Hi-Lo setup params and try to send it to the ECU when online...error comes up saying HiLo config file is not compatible with OEMM800...checkmate!
You can sucessfully (depends on your measure of sucess!!) run staged injectors on M800 OEM using INJ5-8, and having them paralleled with the primaries, and use an output to globally turn on their high-side, but it's VERY hard to stage them very close either side to the switch point....in fact with the setup i played with, it was a LOT of effort to get an acceptable result, using comp tables, etc. It was only that the customer had the M800 OEM already on the car...but I'd get a "normal" gold ECU Mx00 ECU if i wanted HiLO's in the future....
like so many things, you can say "you've done it" but the outcome is not exactly what you want.
Real bummer, as there are a lot of the older M800 OEM's available at reasonable prices/people pulling them out of old cars, etc. Shame it doesn't work.
After you've had staged iHiLos on a high power 4cyl, esp with E85, you never want to go back