I do not think the volume on the charged side makes much difference or the great heads and exhaust. I run a big intercooler and the big Extreme Velocity hat. My motor seemed to like the big hat a little bit more than the small hat. I think Bobb Makely's (Mike Evans old car) has some really good Bulldog heads on it and only runs a D-1. Will check on the pulley ratio that runs when I put the FiTech on it this weekend. It seems to me that Mike dropped blower pulley a lot too. Since your motor seems to like more advance I would kick it back up to say 36 degrees until you see some boost. When I set up my boost timing curve did not pull any timing until after 3 psi. Then pull a lot of timing out of it. At 8 psi my timing would be 20 degrees. For me there is a lot of HP with more timing. I asked about the fuel pressure to see if there is any pressure in the hat. So you see some pressure advance and then it drops back? When I ran a carb (a 950 then a 650) you could watch the fuel pressure to get an idea of what was happening in the hat. When you run NA you want to see 0 inches of vac at full throttle. If you are still seeing 0 at WOT then the blower is not a restriction. Hope my ramblings give you things to think about.