Alright guys, had my r27 for a few years now.. recently got a bit bored of it so had a full stainless exhaust and de cat and the k tec stage one pack so a map filter and a dyno, the car made 215.6hp which I'm quite chuffed with but I've been told the car needs a new o2 sensor which will solve the lumpy start up and idle. The cars runs fine when up to temperature but until then it's pretty much undriveable. K tec offered me one for £86 +vat then an hour labour, but euro's have the sensor for £54! Just wondering how easy these are to change? It's the first sensor on the system out of the two! Thanks guys! Sorry if this is in the wrong place admin, new to this!