I have a MPI 502 with an intercooled M3 Procharger. It was cutting out at full throttle so after checking the timing I started to play with the fuel pressure. It would not go over 4,000RPM. For some reason, it started running much better with less fuel pressure but it still isn't running the way that it should, though it will now run at 4,400 RPM...I think that the pressure is as low as I can go without being too lean. Is there a reason why it would not want to burn more fuel? And yes, they are 1/2" fuel lines. There has also been some white smoke while the boat is coming up to plain. Could this be related to engine temperature? The water temp guage does not move while out on the lake. Is it possible that it is not getting enough air? The air cleaner should be plenty large and it appears to be clean enough... I also checked for codes and none came up. Has anyone had any similar experiences or does anyone have any recommendations?
Thanks

Are you sure the white smoke you are seeing isn'g just steam from the cold water hitting the hot exhuast?

That is a possibility...
The manifolds definately get warm but they don't get so hot that I cannot hold my hand on them.

Depending on the lake water temp, it may steam this time of year yet.........

Check the tension on the procharger belt. Also if you are not running a thermostat it will not move the needle on the gauge very mcuh.

Change fuel filter. I know you said you have 1/2" fuel lines but check them anyways, mine was doing this sunday and my fuel line was collapsing where it feeds the high pressure pump

I changed the fuel filter and tightened the belt on the supercharger. I also cannot find any kinked or otherwise restricted fuel lines. Tomorrow I am going to install new spark plugs and get a new belt for the supercharger...I hope it works.

Are you running a MSD or similar ignition? What is the spark plug gap? Is 4000 rpm about 3/4 throttle? When I first got my boat with a Procharger had stock ignition and bad spark plug gap of .045. Engine pratically cut off above 3/4 throttle. With increased internal cylinder pressure spark canot jump gap. I reduce gap to .030. Made big difference, then put on MSD and put gap back at .045

I would be very careful backing the fuel pressure all the way down without knowing how the motor is burning. Motors usually run great when lean right before they melt a piston.

do you have a boost referenced fuel pressure regulator??
also +1 for the spark plug gap..you said efi,did you get your mefi tuned for the pro charger?