Yup I own a 08 xp summit 800 with a race shop mod in it. 15.5:1 head... the only reason I say this is because I run about 185 lbs of compression here and Minnesota for hillcross but didn't check my compression before riding out west. Ran straight 110 and my sled ran like $hit!! Got out the tester and was only running about 145 lbs. Now I run about 2 gallons of race just to make sure... What kind of compression are you running?? 
