you could put a foam cushion or something in the bottom of the battery box if the banging is that bad...i dont know your waters..
if the hull has more curve upwards than the bottom of the boat i would try to level the battery so it was not setting at a great angle..ignition battery
I agree... stick with Honda OEM
Went to West Marine yesterday and bought their new plastic sprayless fittings. Will replace 3 tank fittings and
Open the idle mixture screws out (CCW) one half turn.
One can read the color of the correct type plugs to determine jetting.