I was having the 'bog' with the two 750s. The car would come up and then drop, then gradually pick up. I spoke with Damon and he asked me how much fuel pressure. I was at 7, and he said they will not launch at that pressure. He said raise it to 8 1/2 and almost all of the bog went away. However, it wants to stall during the turn getting off the track. But I picked up about 1.5 mph. Still working on getting the 60' back to where it was.
Good luck