As usual, Harley is correct ... the XL centre tank fits just fine in the original Bobcat, and in fact that's how I have mine set up.

IIRC, all that I had to do was make a very slight modification to the plywood former that is at the rear of the canopy ; the standard Bobcat had a strip across the bottom of this former to help the canopy keep its shape, and that strip would hit the centre fuel tank. 10 seconds with a Zona saw and a dremel sanding drum will take care of that.

Mine flew with only the 2L main tanks when I was using a small (RAM 500) turbine ; I added the centre tank only when I went up to the P120. So, you could even fly with your original tanks to begin with, then only add the extra tank if you feel that your flight time is too short.

Gordon