I have 454 with pro chargers and cross over kits.
The T stat housing just has two ports each to x manifold.
At the crossover there is a bypass to the intetcooler.
It had no stats when I bought it.
I was going to install 143 high flow stats but will the exhaust get too hot before the stat opens
????

I would say no thermostat.

You need bypass to get water to the exhaust if you are using t-stat, in my application i have try t-stat and cross over with bypass without success, they made steam poket in the block and the stat dont open at the right time, you need to drill min 3 to 4x 3/16 hole in t-stat to help with temp consistency.

Even with the bypass you still had to drill holes in the tstat.... I have the Hardin with bypass and now i am thinking from your post I need to drill holes in mine.

thanks
Bryan

Why take the chance? What does it take to clog a 3/16" hole? If clogged, no you're back to steam pockets....

Ditch the tstat when running x-o

Have to run the stat, otherwise I don't get any temp.... To much water flow even with a restrictor plate... Only saw 110 at wot.

I have never got a 3/16'' hole clog in t-stat in 3 years with that setup without sea strainer, 3/16'' hole is prety big, you do not need only 1 hole but you need minimum 3 hole in the stat to make consistency.

I ran stats two years ago, and none last year. I think I need to restrict alittle water to the exhaust. The flow thru the inter coolers without stats is low.

procharger says no thermostats...