I did mine myself.
The base of the Bostrum seat is much broader than the small 4 hole pattern of the original post mount. I had to get a quarter inch thick aluminum plate the same size as the Bostrum seat base. Then I bolted the new seat base to that plate, and then was able to position bolt holes through the plate into the most suitable mounting points through the floor.
I got the little air compressor from the same supplier and bolted it on to the front horizontal frame member, just behind the front plastic grill. Then it was just a matter of routing a quarter inch air line from the compressor, up through the floor under the seat.
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