In my setup i used a piece of 30x30 PGI mounted on the holes of the seat bracket, then wafer screwed the bracket for the extinguisher into the PGI, Looks great tucked in under the lip of the seat and the seat can still go back and forward all the way without getting obstructed from the extinguisher.Also doesnt interfere with any leg room.

Cost me About $30 for the extinguisher and the PGI and screws i had lying around. You will also need a drill with about a 10-12mm bit, and a screw gun with a philips bit to get in the wafers. Took about 30 mins to install.

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Quickest Pig in Perth