you would get the best price on parts by getting a vendor quote on here. you can get a good trans that will hold plenty for under 10k easy. You just have to decide where you want to stop for power and what you plan on doing with the truck. Then you build the trans to match. BHAF is a big air filter you put on rather than buying an air intake. To hit 400hp on your truck you will need some injectors too then a turbo as your egt's will be pretty dang warm at that point.