I recently " first hand " learned just how much the cooler brings the temp down , my 450SS has double coolers relocated to the front rack , so the cooler hoses are right in front of the handle bar and I can grab it while sitting in the seat and after rebuilding the engine I was constantly checking the temp , I have the fan on a toggle switch ----you can fell the difference of the inlet and outlet hoses and when the fan is off or on -----speaking of fans , I have two fans , one is still on the engine with no cooler in front of it , I don't see the fan blowing on the engine does much
