I know of good test for ATT. I 64 in WVA Sandstone Mt. Its 7% once you reached the top the att. is 2748 ft. My always hits 210 climbing it tnat empty I hate to climb it loaded! From all the reading the ATT should help out alot! Last time I made that run was moving up to Ohio in April and I was blowing black smoke all the way up! It does cool off at the top.