A friend just purchased an 03 Dually HO 6spd and wants to start bombing it. I just wanted to help get the right stuff the first time. He wants it to be a sleeper that hauls a**. I told him to start with some injectors in the 50-75hp range and some gauges. The truck is already muffler delete and AFE equipped. I just want to point him in right direction get things he can build on to and that are compatible together like what is the best first box to get to stack onto later.