Getting ready to do mods ????

[907DAVE]

It is a warm-up valve.

When engine is cold the computer will close that valve in an attempt to keep some heat in the engine for faster warm-up times and reduced emissions.

Some guys are using that valve as a exhaust brake, though I am not sure how effective this is. I do know this can create added backpressure and you run the risk of floating exhaust valves.