My experience is limited to my own runner 180. First tune round was a malossi 172, and a pm pipe, early type not the curly-wurly one. Up-jetted to suit, all the rest was standard. Iprovement was dissapointing over stock, maybe a bigger carb would have been better but wanted a stock looking motor. It was an improvement over std. but not as big an increase as would have anticipated. Second incarnation was a std. 180 barrel ported and flowed to duplicate malossi barrel, and was better than malossi version, all rest as above. Third and final (for now) version use a standard barrel bored out and replated to give me 189cc. malossi mhr crank. again pm pipe, std. upjetted carb and air box. Change to polini variator, and uped roller weights. malossi delta clutch std belt. this gives me over 24bhp and off the clock speed wise. Clocked at 85mph two-up on dual-carraigeway for 10miles! All have been reliable, but current version is quite fun. Big carb, better pipe may result in better acceleration, but I dont feel it needs much more and would like to retain a semblance of reliability. Overstroking to 54mm would give me 196 but laid out for crank on 189 conversion so we’ll see. Taffspeed should have barrels done by now, if they could get barrels, dont know.