How bad is it to drive with a missing header bolt?

The one on the driver side in the back is missing. I figure this is why I am getting a ticking sound when I step on the gas.

 

Yea, thats prob it. I couldnt image it being that bad without it... just obviously have an exhaust leak. If it were my car, I would drive it if I needed to.

 

Are all the other bolts tight?

 

I don't need to drive it, but the weather is nice so I took it into work today - :P

All the bolts are tight. I am just tired of the ticking sound and the exhaust leak. I am told I smell like Gas from my wife - :P

Is there an easy way to get this bolt in? It's in a very tight space.