I asked kev 3 days ago who makes them as I just bought the fuel mod for my 07 xt660r and I asked him is it ok to fit the fuel mod before the 02 controller turns up as not bought it yet buying it this week. And he said no you have to fit the 02 controller with the fuel mod or the OEM 02 sensor on the bike stops the fuel mod from doing its job And he is the one that makes them ? He said if you fit the fuel mod the OEM 02 sensor will just take the extra fuel away that the fuel mod adds so you have to fit both mods for it to work right which make perfect sense.here is his reply to me asking the question......

‘You can fit the fuel mod but the O2 sensor will just take the fuel away that you add, yes you need both mods to work together’