just remember this is not a carburated v8 ... meaning the computer has a preset cold start mode it will run in until the coolant reaches a specific temperature, while in this mode fuel mixture and timing are much different than at normal operating range. putting different thermostats and coolant additives in may just bring you down low enough that the ECU stays in cold start mode. my previous experience with a few vehicles all resulted in retarded timing and a rich fuel mixture. not sure how the programming in the crossfires ECU reacts to colder temps or where the cold start mode cutoff is.

Anthony can probably answer that much better as he uses and sells a cooler thermostat...