I race my 2000 GMC sierra 5.3L in off road sand drags. These drags are in 4 LOW RANGE - 300 foot long track. The problem I'm having is the transmission will not shift in 4 low with too much throttle. I have to back off the gas to get the tranny to shift 1-2 or 2-3. You guys know of any programmers that work in 4 LOW?

Thanks

 

Nobody?