I am looking at headers one says with air injection and one is with out how do i tell if i have air injection or dont 2001 2door 4x4

 

The secondary air injection (AIR) system helps reduce exhaust emissions. The system forces fresh filtered air into the exhaust stream in order to accelerate catalyst operation.
You will have an AIR pump mounted on the front of the engine (driven by a belt), with hoses and valves leading to the exhaust system.

 

The AIR pump on a '96+ is located under the radiator and is electric. You may or may not have one. You can look for the pump by removing the front air dam under the radiator. Or look at the codes on the RPO label for K18. If you have K18, you have the electric AIR pump.

Here's what the intake tube looks like:

 

Probally dumb question where is the rpo code and if it has 18 in then i have air induction?

 

The RPO sticker would be on the inside of your glove box door and as Kyle said, it would read 'K18'.