Why won't it run hard on the backside?
Also i think your converter is the culprit here, I have witnessed a number of yank SS converters under perform, I had a SS3400 and it was complete garbage much like this, picked up 3mph changing it
Also for reference, this is my timeslip, stock 346, heads cam, 4.10s 295/65 M/t stock trans and a PTC 3800 1.8STR.
3400# 1 3/4 headers, 3" full exhaust and LS1 intake, stock throttle body







