Hi,this is my 1st post,just bought myself a 52 plate wrx with prodrive kit,otherwise completely standard.Only had car a few weeks and engine managment lights been coming on 90% of the time.Took it into stealership today to be told the high flow cat has been removed causing lack of power and the eml to come on as a standard cat is now fitted.found this hard to believe (£800 plus vat) so went round to workshop and spoke to mechanic there who tried to flog me a prodrive cat which was fine until i happened to say it was a wrx,which he then told me he never realised and the cat on the car IS the correct one!what kind of scooby mechanic doesnt know a wrx from sti?anyway reset fault codes,checked boost is at 15-16 psi,went away with light off,10 mins later lights back on.dont notice much diff in power when light is off,feels like 180-200bhp not 250 odd.any ideas?i think maybe maf or lambda sensors but dont know....they checked timing which was ok too