I totally agree on the 135 IT. Personally, I think the lower temp you can cook, the longer it takes to get there, the better it turns out. If I'm really prepared, I'll dry rub the night before and keep it in the fridge. I think it turns out better that way. I don't usually sear mine, but if I've got my gasser going too, I will. EVOO works well, especially if you're gonna sear. A little worchestershire bath if you're just going straight indirect works nicely too. You can do a lot with tri-tip, but most importantly, don't overcook.
Eddie G. - Smoke Bomb BBQ coming off a Lang 48 Hybrid Deluxe