I have a carb 5.3 but got to thinking when I buy my new m s d timing kit. If I can use it for e fi without using the stock harness and ecm..is it possible if so what's need other then intake and tb

 

You have homebrew options such as Megasquirt. Google it and then peruse LS1tech to see what guy are doing with it.l

 

For fuel control you either need the stock ECU, or megasquirt and the MSD LS timing box. Personally with the flexability built into the stock ECU I don't see much of a reason not to use it unless you're going HUGE.

What are your goals?