LS3 - 408 Popping - 6L80e not shifting ....

[6600DURAMAX]

Having two separate issues

1. Have a Blueprint LS3 - 408 - makes 595HP engine almost 400 at the wheels - running a PSI Harness and a 6L80e trans - full length headers into dual 3'' stainless exhaust with "X" pipe and 3'' BORLA ATAK mufflers. Engine has about 500 miles or so - oil changed since break in also installed new plugs and Scott's Performance wires.

Question that I have - when accelerating at roughly low to mid throttle input the engine wants to pop through the exhaust - this is especially noticeable right before it shifts. Been to the tuner twice and he states it is not running lean and that it is impossible to tune it out 100%

I'm at a lost here - thoughts suggestions.


2. Have a 6L80e behind a LS3 - 408 - the transmission has a Yank Pro Truck 3200converter in it and is being controlled by a PSI Harness

Question - if I am driving the truck normally - the trans shifts normally ( all the way into 6th gear). However if I accelerate hard, do a burnout, ect..... the trans will not shift all the way into 6th - seems to shift to 5th and just stay there. If I stop and shut the truck off, restart it and take off all seems to be normal ??
The other day the trans wouldn't shift out of 2nd gear( I think it was in 2nd) ....... drove for a mile or so - shut it off.... restarted it... all seemed fine and shifted all the way to 6th

Ideas on the cause of this ??

Any help on either of these issues ???