I recently installed a Defi blue racer boost gauge in my car and the airbag light came on. Anyone know what i should check?

How did you connect this gauge? This will help us understand if you might have disconnected something.

If you removed the factory dash clock, with the passenger airbag light like my '06 has , this will cause the airbag light to come on. I fixed my light, because I want to know if there is a real airbag problem, by plugging the clock back in and putting it in the dash, under the gauge. It (the clock) unscrews from the housing, and is quite small. You could check by plugging the clock back in, if disconnected. If this is not the case, I would check for loose connections near/ around where you were working.

i have an 04 and i went through the wires below my steering wheel on the left. I noticed today on the highway it went off for about 5 minutes. but once i pulled into my work parking lot it came back on.