For the guys concerned about HPFP drops, you’ll see in my Stg 2 5.8 E30 logs earlier in the thread that mine will drop to 1500-1600psi (with no issues) on the initial pull, and then stabilizes and meets target on subsequent pulls.
From doing a ton of logs, driving, and playing with E mixes, I’ve come to find the big HPFP psi drop is probably mostly because of how BMW programed the stock HPFP to respond.
For instance, on the same drive I can have the car on cruise control for a while and if I do an immediate acceleration, the HPFP will dump every time. If I instead do a couple of half throttle applications and then punch it, the HPFP is fine.
It seems like it’s something in BMW’s control algorithm for the pump that doesn’t let it respond quickly enough when it’s been chilling for a while and then you ask it to immediately max out. But, that takes me back to my Chemical Engineering process controls days that I don’t want to relive.
Either way, down to 1500psi has been OK from my testing.