Fass or air dog?

[Underdogpsd]

I've got a 95 7.3 4x4 single cab long bed, it's got a 4 inch dp all the way out and a edge 1500. And It only has the front tank for what ever reason. I'm wondering if someone could point me in the right direction, I'm looking to run bigger injectors, hpop, arp head studs, new pistons and all. What one is going to be better and how hard and what am I gonna have to do to install it? thanks guys