Like Rex said, a lot of the fuel mileage is driver/tune/header-pipe combo.
I'm on the 2108 w/ 659704 and now that the engine has about 3 gallons through it, it has really woken up.
I haven't "risked" going 10 just yet, but I know the engine has it in it. I always come back with more than enough fuel to know I can go 10, but I've always gotten burned (in the past) in some way by not making it if I have to push super hard. Not to mention, the latest tracks I've run on really like full throttle.
This past weekend, I was pitting around the 8 minute mark and my pit man said it was taking around 75cc of fuel via the gun measurement. But I was on the hammer hard.
Anyone that was at Barnstormers this weekend can vouch for the power this engine makes, yet how smooth it is to drive. I love running against modded engines in a straight line and pulling on them.
