With G-tech testing (I know, ultrareliable
)and my relatively low compression ratio, my car had the best mph with 39* of total timing with 94 octane gas. As soon as the track opens I'll try a couple of different settings but last year a back to back with 34* to 36* gained me a full mph on a run with a quicker 60' time and all my runs after that were a mph higher than the 34* ones so that suggests that I definitely gained some. The timing window for a 5.0L with less than 9.5:1 is about 34*to 40* and every car seems to like something different than the next.