I do tri-tip a lot of different ways. The easiest and best bang for my buck is the tried and true reverse sear with Spade L Beef. Smoke to 115 and then grill at high temps until 128 or so then rest for 10 minutes or so.

But if I want to get crazy, I'll do rub with Spade L, smoke with the lowest temp I can get to about 100 - 105 internal temp, pull off and then vacuum seal and sous vide at 130 for 3 plus hours and then grill at the for 1 or 2 minutes on each side at high temps. Slice and serve. It's ridiculous.