i went from 9min in my .19 speed to almost 12 (when pushing my luck) by going up from a 6mm to a 7mm restrictor, going down from 30% to 25% nitro, going down from a p3 plug to a p4 plug, setting my EPA on my remote for my throttle servo at 80% of max, and running a cooler just for good measure. in my experience, the most runtime will be yielded by good trigger finger habits and the above stated tricks.