Its pretty easy to hop up these trucks a little its taking them to the next level that gets difficult. Fuel pressure is a big deal. The first gens injectors pop at ~3550, second 12 V ~4000, 2nd 24v ~4500, and the 3rd gens stock up to 23,500 psi. Big difference in the amount of fuel per unit of time. Better atomization at higher pressure. Cleaner with more power. The first gens are certainly easier and more economical to work on though.