Hi Rob, I fitted the o2 sensors to my SS with megaphones (custom made with o2 sensor inserts) , when I plugged in an OBDII scantool I could see the ECU adjusting the fuel trims and switching into closed loop mode. Pretty sure someone in the factory told me that it would make use of them if fitted. The only difference was switching off the ECU error reporting if it couldn't find them (ECU would just use its internal fuel maps 100%). Anyway, I've purchased an SC Delta 400 and the bike is getting mapped this week. If you have any factory tips/tricks for getting the most out of the engine I'd very much appreciate a pm/email.