Sorry if I appear stupid but what do you mean +1. I agree fuel will make a big difference. The fuel I just switched to is sold and used widely at our club, AT Racing 10% Syn 5% Castor. I have just increased from 20% to 25% mitro since learning that the GRP 21 Tuned is shimmed for 30%,looking to get more bottom end. I also uped my clutch springs to 1.1mm. Yet to see if the wheelspin can be limited enough at this setting to improve lap times. If I can get it to bloody idle for more than 10 secs.