It is all about trail and error. If you are a car show groupie then run a clutch and you can not hear it when the car is shut off. I have run and electric water pump drive on my motor on the street cooled ok but was a better choice for the track. Right now I run a 26 inch nice clean factory rad, mated water pump and housing rad has the shroud.I do not run a clutch on my factory 7 blade fan. I also have a hi flow thermostate 160. It is a 430 ci Hemi and it is more than stock and see a lot of RPM. Mech. gauge shows 163 degrees.I have driven it in 90 plus degrees and it still runs 163. I can see on the gauge move when the 160 opens up. These clutch fans have some noise to them so you might have to live with it. I have seen more than one fan come apart at the track so High RPM might not be a good thing for the factory clutch. Your choice of what you use, some times there is no answer to your question until you play with parts.