When my truck was totally stock, my times were also consistanly SLOWER in the tow haul mode. I've made a ton of passes on the Gtech, and although the ET was slower in the tow/haul mode, the MPH is usually higher.???? It did feel better tho, but TM was also more noticeable. I leave mine off, especially now with the HPPIII.

 

Mine is mostly stock too. If I go from a dead stop the ET is higher but the MPH is higher, if I go from about 20 stomp then my times go down with the OH on than it would with it off. I guess all trucks run a little different.