Hello I am going to be fabbing up a diy kit for my 99 silverado with the 5.3L. I want to run 4 psi just to add alittle bit since its my DD. I am planning on running non-intercooled. My main question in fuel. I would really like to keep the stock injectors(not sure what size??) and fuel pump if possible? Not going for tons of power just alittle more than stock.

 

Since the stock injectors seem to operate at close to max efficiency at WOT on a stock engine I would suggest upgrading them. You might be able to get by with some regular 8.1L injectors, but would probably be better off with the 8.1L marine injectors. You are only planning on 4 psi now, but if your going to bother I would build the fuel system to handle about tripple that. These engines can handle a lot more than 4 psi and still last a long time. Even if you never end up using more than 4-6 psi, at least you will know your fuel system will be more than adequate for safety and longetivity of the engine.

 

99's had 19# injectors. If your only going 4# of boost you may want to get some used 24# from a 2000 and up. I'm sure you could pick some up from someboby on here for hardly nothing.