I run one and with a by-pass and thermostat works great, one less drag on the engine...Rob

I've got these on my Teague 720's. I think I would like to have therms but Teague says no.

I always changed mine to crossovers, never had a problem.

I have the cross over on my engines. I have a problem with the cold water in the cooling jackets causing much condensation in the oil.The inside of my valve covers and under the intake manifold is covered in a milky mess.I put thermostats in 140' drilled holes to release any steam.I over heated the engines and the rest was a total rebuild.Now for my conclusion!The circ pump moves the water through the block and absorbs the heat and maintanes an equal temp,thermostat opens and dumps hot water when the right temp over to the exhaust.The crossover is good for all out high speed (high RPM) lots of heat.As soon as you back off mid range and idle you get the engine cold.The crossover with a thermostat does NOT allow the water to circulate untill the thermostat opens and you get hot spots in the block.This year I will be putting the circ pumps on with thermostats.The seawater pump just delivers to the engine and the circ pump moves the water around the block.This was my expierence.

Thank you for all the infomation on this!
I was looking more at the clean up "look"
But, agree don't touch

It's like when you were 2 and that Mr.Yuck sticker was on the bottle of DrainO - You think I would have learned then, lol