CEL caused by MAF (or lack thereof)
 

A while back, I bought an Injen cold air intake for my 2004 Tiburon. My first mistake was having a friend install it to evade the cost of having a mechanic install it. After the install, my friend handed me a piece of my stock intake (The Mass AirFlow Sensor) and said, "Hey, this piece doesn't fit with you new intake, but it won't cause any problems". Well, when I went to get it inspected, it failed due to it not being there. I was wondering if there was anything that could either trick the ECU into thinking there was a MAF installed, or a device that actually did the job of the MAF yet took up less room. Any suggestions would be helpful.

No, I don't think there's anything you can do. The MAF is a critical part, and without it, the ECU falls back on default setting for mass air flow readings. It is comforting to know the thing still runs with it disconnected.

I think you're going to have to put the old intake back on, at least until you pass emissions.