Yep. I tried to advance the timing on Bill's Custom Performance, and immediately brought it back because the valve were rattling. Do you have any idea how far it's advanced in those custom tunes? Just wondering how much is (clearly) too much.
Drove to Auburn, AL last weekend and got 15.8 MPG on the Custom Performance tune. The tankful was probably 90% highway, but some idling around town getting out of game traffic. There were five people, with about 70 lbs. of sousaphones (marching tubas) in the bed.
I feel like I should be able to do a little better than that on the highway. Before I had my tuner, I actually got 18 hwy going to and from Auburn (just went, then came right back, so it was ALL hwy.
I am giving the Tranny Only tune another try to see if it's higher or lower than the 15.8. Obviously it's not a direct comparison because this tank will be only about 30% hwy. After that, I give the stock Towing a try.
I always calculate my MPG when I fill up. I WISH I was getting what the Gryphon says
