I got up to 28* and it was harder to cold start so I backed down to 26.

When I had the cut delivery valves installed, the engine would bog down and rattle like hell if I floored it below 2000rpm. They may have just been quenching the flame with too much fuel but I know altering the delivery valves also alters the injection timing because of how it changes fuel flow. How much, we don't know yet.