Well, double trouble.
First question; can the 2003 air injection system be deleted ? My 2000 never had it. What do you call that? SAI? Where is it mandatory ?

Hate its black interior, love there is no rainroof...

 

2003 - very few Non-SAI trucks in existence. So difficult to replace the ECU with one programmed for non-sai because the program is different than the 4.0 trucks. It is possible to get it programmed but you would need to find someone with a testbook, I know Eurover in Greenville SC used to have one. Then of course you would need to plug the head ports. Its a giant pain.

 

I know of an 03 near me without SAI and I agree the stuff gets in the way while ya work on it, but honestly it works pretty good. #1 issue is the 3 rubber dampeners crumbling which support the pump, and the little ends cracking on the vacuum lines. Besides that the system works pretty well. I've had 1 pump die, but that was an easy 5min swap with a good spare.

 

In the end it's easier to keep the SAI going vs. all the trouble of converting it.

 

Have a 2004 4.6 with SAI deleted..
Should get the machined bolts to plug the ports on the heads instead of the welded shut originals stuff.