I have noticed that when I let my truck idle for a minute or two then take it out it runs best right at about 160 degrees on the temp guage. I mean it sounds way different pickup feels better, not WAY better but better. Anyone have ideas why its like this? ANd I mean it really sounds better. Sounds like a different truck. I don't know how to describe it, my friend's dad's 383 Big Block Mopar sounds similar when he gets on it pretty good. I seem to think its the secondaries opening up and for some reason tehy open sooner when its cooler. Anyone have an opinion? I am close to puting a 160 degree thermostat in it.