It works almost perfect mounted behind the passenger seat. The holes in the L bracket had to be enlarged so the seat bolts would pass through. The seat travels far enough back for me and my neighbor to ride with plenty of room. With a 2.5lb mounted to the bracket the seat bumps on the extinguisher in an area that is covered in carpet so it won't be damaged.
Now for the warning. Do not put any of the bolts into the bracket without anti seize on them. As I was testing the fit I put the end cap screw in with my fingers. Now as I did that I thought "stainless on stainless better put on some never seize" but I chose not to for fear of getting it in car during the initial fitting. Both cap screws were 1/4" from being tight. Once I confirmed the bracket would work I went to work on the bench fully assemling it. One of the cap screws froze about half way back out. I spent the next hour soaking in lube and working it then tapping and threading. The cap screw never felt in the least bit snug until it locked. Don't do it! Unless you have a 3/8 16 tap and die plus an hour to waste.