Hey mate when i used to run a highflow on my 13b the boost control issues became worse, finally got it sorted by welding up the internal gate flap and putting an external gate on the manifold so that might be something to look into. Shortly after that my 20 was into the 10s running 10.60s @ 125 :P had a jatco 3 speed in it, transbrake, was running 16psi with a 40 shot on the brake, pump fuel, i was thinking at the time that on race gas and 20 odd psi plus a little more giggle gas and 9s would be possible on a good run. My highflow had a bigger front comp housing etc so probably no ordinary highflow.