Yes, brine it!
Also good advice to take the temps, and to tent the tenderloin with foil for several minutes after it comes off the grill. Not only does it continue to cook a bit, but it allows the juices to settle so they don't run out all over the plate as soon as you cut it. Even a well-cooked piece of meat can go dry if it's cut too soon.
This is a great recipe for pork tenderloin on the grill, one of our favorites: Chipotle Crusted Pork Tenderloin
. I only use 2 tbsp chipotle powder and it does have a kick. Along with other sides, I serve it with chilled fruit to temper the spiciness. Good luck! :)