I'm not entirely sure that was surge, might have been some MS hiccups. They seemed more likely to occur when the engine was cooler (E85 seems to like a hot motor?), and when the motor was nice and hot it would crack off real clean full boost pulls. Which makes me sort of think it wasn't surge? And if it was, maybe improving the flow through the head (intake, ports, cams, up until it hits the log) might help?
I just need to get that log mani welded back up with something better than my 110V MIG. Maybe I should troll CL for a better welder, and run some 220V out to the garage. Or jsut take it to a welding shop, probably the better idea.