I've decided to limit my fleet of engines to 5% nitro. More compression requires tighter engines which drives up the price. If you think about it ,turn an engine at 16,000 rpm instead of 12,000 your wear out your engine by 25% more so lets say at 12,000 your engine lasts 4 years and at 16,000 3 years. buy the bigger engine and turn at less RPM for power. Pocket the savings in lower cost of fuel toward the next purchase of replacement engine and at an extra year later.