clutch upgear

iam running a t5 172 reedvalve with a pm pipe what clutch would be best for this set ie 20,21,22 or 23 tooth. it is a std 172 with malossi reedvalve and 30 mil del and modified std crank cheers chris

Where do you drive mainly? More in the flat or in the mountain? What primary you have, 65 or 68 Z?
I drive a a Malossi 221 ccm with 30 er Carb and race crank. I have the primary 23/65 Z with the gears from PX125. Power on rear wire ca.20 PS. Highspeed ca. 115 Km/h on bicycle speedometer.