thats not true if they are converted properly they will run fine.

ive just had mine done,with a supperchip ,it goes like hell now with 135 bhp and loads of trq.well worth the money.

nines an 03 plate it was flat on power,i put a k&n on it not much more go,then i was told to change the air flow meter.with the k&n it flew.but ive also just had mine superchipped,now it really flys 135bhp now..:D