I can say that the B6 does get better mileage than the Speed. Also better mileage than the plus 4. Ron has designed this engine to do so. He smoothed out the bottom end which has increase run time over a B5 and +4. Some other tweaks were done in order to keep up the performance as well. The B5 and B6 cranks are harden but not coated. The cranks will last 3 plus p/s changes or resizing. I'm not saying this thing is better than the speed in longevity (haven't gotten that 15+ gallons on my Werks yet) but for the price and mileage its well worth it over a speed.