Silly question, is there a converter still in the exhaust?
Take all the air out of the bag and pull more first gear fuel. By the time your mixture catches up to the boost, it starts to make decent power. Before that, it's too rich / can't burn what's there. That's why boost comes up/blows the tires off a few feet out.
I used to run 115 mph on a little 49 and stock cam. Stock everything in the rear. 26' D/R. 11.8's all day.