P160 at least - preferably a Rhino or equivalent (16-17kg range). I used a Rhino in Ireland - perfect for the job!
Remember that the F4 has a Delta wing shape. It bleeds speed off in the turns very quickly.
For interest - my BB F4 weighed around 16.5kgs WITHOUT fuel. I believe that a P120 would not be able to handle the F4 safely.

cheers,
Leon