With the stock pulley on the Eaton M62 off a Mercedes, the flow differences are @ 1.1% improvement over the SC12. Even though the displacement of the M62 is 1000cc as opposed to the 1200cc of the SC12. the pulley is smaller the than the SC12's and it spins faster. All I rwsally have to go off is a rough measurment, the SC12 has a circumference of @14", and the M62 has @11.5". The M62 should be very close to the SC12 with a more efficient flow and lower exit temp than the standard roots type supercharger. Not sure if I have the USDM or JDM version though. OK, the measurements I have are loose at best. i measured the pulleys on the outside of the grooves with a seamstress's tape. The stock crank pulley is @ 18". The pulley on the SC12 is @ 14". The pulley on the M62 is running 11.5". The difference in the RPM of the Supercharger driven at an engine RPM of 7000RPM is the SC12 at 8,960RPM anbd the M62 at10,960. At this rate the M62 flows a little over 1% more air than the SC12. The SC 12 has a displacement of 1200cc per revelution, the M62 is actually 1016cc. The SC12 is limited to an RPM of 12,500 RPM the M62 is limited to 15,500 RPM. The M62 is more efficient! It has a lower high side temp than a standard roots type supercharger, and has a lower drag on the parasitic drag on the engine. For S&G, the M90 has a displacement of 1472cc. So I still want to try the M62 on a 4AGE.