I documented more than15% fuel mileage loss at 65MPH by switching from stock to MCP. I did this testing back to back, on the same highway, at the same temps, over a measured 100-mile course. It did give a small increase in WOT performance, measured by the time accelerating WOT from 50-70-MPH. It did it about 1/2 second faster. Is that worth a 15+% loss in mileage to you? It wasn't to me. The KLX kit loses about 10% fuel mileage. .
