That front stock mani is going to hold you back some, but plogs go for the price of knockoff headers these days and are the welds on those are ****. I'm running ct kit with front powerlog and reworked rear manifold, with the #6 primary turned toward the crossover. The problem with that is its a ***** to get to cylinder #6 spark plug with the wastegate there and primary in the way. I haven't had any problems with the plog yet tho.
Did you just run the CT kit wastegate perch and run a pipe from the wastegate to ground? I've been thinking about this but not sure if I should have a perch made without the flex section.
You should be able to get the smaller booster from 01+ montes/impalas