I have one in the rear above the useless cut out and one under my drivers seat they are both halon alot more expensive but the work great and do not make a mess. This is coming from experiance those damn cheap yellow powder ones are a nightmare to clean up. But the worst part is when you get everything spotless then turn on the heat

 

I used one of the bolts that used to hold my spare tire bracket in the back.

 

Picked mine up a Home depot I think. Screwed the mounting bracket to the trim by the drivers seat. Never had to use it, but its quick and easy to get at,...