Did you break it in according to the HPI manual or did you use the heat cycling method? the Heat cycling method will allow your engine to see up to 10 gallons with excellent performance, maybe more.

The break-in according to the manual will not allow that longevity..I should not say that really, my very first K4.6 I broke in according to the manual and it ran until 10 gallons, but its performance dropped to that of an S25 at about 7 or 8 gallons.