" Dead Man's Curve" playing always some how dropped my MPG ! I see your 15.2 and raise to 15.3.
Dart sportsman's block (oops, wrong site) would be a great prize to display in the shop!
302 with the 4:88's gave me around 10 mpg if I remember. The 400, a good solid 8 mpg. Mind you I never let the carbon build up.