I tried the six pac on my 64 440 race car, stock 74 engine with cam. Blocked the bleed sec hose and jetted up a little, ran no better than the 850 DP on the Torker. Now racing class the six pac is better than that AVS. My Plym had 3800 vert, 4.88 gears and 14-32 slicks so no problems there. I agree with Zippy, de-tuning the Hemi and pumping up the 440 is not real world. All about port velocity and volume, after 3500 the Hemi says “can we play thru”