smaller diameter less strength it will have... for instance my clutch/flywheel diameter is way bigger then an stis. i have an aftermarket clutch thats good for 600wtq and doesnt feel much harder then stock now to have an sti clutch rated for that the clutch pedal will feel wayyyyyy harder then stock

the smaller the diameter the more pressure you need to hold a certain power level that a larger clutch can handle with less pressure

im sure its not much different between the size of the wrx and sti but like stated why cheap out you want more surface area anyways