I would skip those headers. The only thing you will probably notice are increased under hood temperatures, and maybe a melted plug wire or two. Long tube headers are the only way to see a decent gain, but they come with a price tag

 

I like the idea of doing this throttle body and manifold as well as long tube headers solely for the simplicity. Your not adding another part to your engine like a SC but the down side is the gains won't compare either.

My concern with a set up like this is would you see increase benefit using a stock ECU?

 

You cant put long tube headers on the 3.6l. They are built into the block. The new Diwali tuner will modify for cai. Since it is not boosting pressure into the manifold it should be able to read the additional airflow entering the engine by several sensors and automatically adjusting amount of fuel.