I broke a belt tensioner playing in my 04.5 6 speed, tensioner went in to the fan, fan got in the radiator, etc. Pricey day for me. My bud has snapped 4 or 5 tensioners. Also has an 04.5 NV5600. We don't know the cause. My theory is the fan clutch kicks on during spirited driving and the tensioner can't take the loading and unloading while banging gears. I also blew a plug on the back of the head doing a 3,700 RPM burnout, didn't realize it, and burnt the engine up once. Another pricey day. I would also lose the Dr. P pressure box and make power any other way I could. As I cracked 3 injectors running their 2025 "Race" box and a capped rail. This was back when capped rails were still all the rage. Another pricey day. Drag racing a manual trans truck is a surefire way to spike rail pressures and destroy our sensitive injectors. After all that, I just parked it. Just a little first hand experience for you.
With a manual trans truck I'd suggest these parts in order.
Enterprise Engine Coolant bypass kit (best bang for buck)
Spare belt tensioner (it WILL break eventually)
CAM (go as big as will fit the first time)
Caltracs or similar traction bars (light weight)
Valair triple disc
Try to get TNT-R. I had/have TNT-R and it works well but, like someone said above, level 7-9 aren't the only levels on the box. Then race the snot out of it. Your times will come down with experience.