I have a 21 Ft. Spectra and I'm getting ready to put a Blown 572 in it as soon as my pistons come in which will be on the 28th. of this month. I have a set of C.M.I. double wall headers and I had it plumbed so the water came out of the pump, through the headers and THEN into the motor. I had it running on the hose 3 weeks ago with a 496 an the motor ran for about an hour and got to 180 degrees, unfortunately, the moron that sold it to me didn't have any head to piston clearance and lied to me about the pistons that were in it and when I revved it up past 4000 rpm's the #8 piston hit the head and disentegrated the piston, rod and block. Needless to say this was a great inconvience. I should have my 572 up and finished by mid July. With the intake I have there is no provision for a thermostat, I plan on cruising long distances at around 2500 rpm's. Will the cooling system work with the cmi's plumbed first? I ran a set of Stellings like that on my Sanger and worked great for 10 years. Would get to 190 to 200 in a long no wake zone and cool down to 140 running. Thats what I'm looking for with the CMI's. Any input would be appreciated. Keep in mind, I'm in Michigan and the surface water is always colder here.