Anyone try any trans tuning to improve fuel economy? My new daily commute has me on surface streets quite a bit now and I noticed that the truck shifts quite late compared to my gassers - probably 500-600 rpm later. Also, in looking at the stock tune it looks like they wait quite a long time to engage the TCC in the lower gears - any reason GM did that? I'm sure there is probably some mpg on the table there, just wondering if there is any possible harmful side effects if changes are made at really low loads (I am typically below 25% tp).