Hi Ian,
I never had any issues when I "converted" to side exhausts, but before I certainly did and it was certainly the MAF sensor. In the end it did keep cutting out. It may be that they might be a bit dirty - might be a cheaper fix!
By the way, if you pass slowly past "new style" parked minis I have noticed on a number of occasions the exhaust rumble sets off their alarms!;)
