When I picked up my Cabrio a month or so back the former owner/builder suggested I may want to put it on a rolling road as all his tuning had been by human senses and basic checks. As it was was feeling a bit flat to drive and throttle response dull I decdied to do so. I took it to an outfit in Uxbridge and they had it on the rollers all morning. Power was 90hp when I went in and 95 when I came out. More importantly it was running rich in the lower rev ranges (hence the flat feeling) and lean in the high rev range. They rejeted the carb and set it up so mixture was even throughout. Its like a differen car to drive. Well worth doing if you think your car is not a peak performance (cost about £140 - this included jets and replacing fuel filter).