Dinqua, I have the 904 Wiseco pistons with the boreded nikasil (sp?) cylinders. No problems at all. Supposed to be 10.5:1, but I suspect it is slightly lower. Had some oil usage, but that got fixed. Turned out to be a bad valve guide stem seal. I always ran mid-grade even after the big bore work, but, changed to premium last year. It seemed to run smoother and my mileage is slightly better. Maybe just enough to offset the cost. No noticeable difference in power.
My bike also likes non-ethanol fuel the best, but I can't find it around here. When in NC, I was buying non-ethanol fuel and my mileage was consistently 10% better. If I could buy non-ethanol mid-grade, I try that.
