become a hypermiler.. or pay the price!.

[Nilao]

My 09 387 just can't seem to get out of the high 6's. I keep the boost under 20 but it doesn't seem to matter. Empty I can be in the 8's but I'm usually loaded heavy with racing fuel. Could be the tires....XDN2 are very high rolling resistance....could be an injector issue as I do notice a shudder around 1350 rpm plus I've had a it run after the key was off twice in 18 months. Thought I had solved it replacing the actuators and shut off solenoid that had 1.4 million miles on them but it did it again a couple days ago.