RE: CMP/GSP Spitfire
Joe,
There are two hole on the top of the cowl, but on this particular photo I have only plugged one of them. They were simply to allow access for an allen key to tighten the two extension wires (choke and main needle) that come out the side.
I have mechanicalo retracts so yes, I thought it wise to have separate batteries. 2000mah main and 1400mah for the retracts. Maybe a bit OTT but better safe than sorry. You only want a less than perfect landing to bend a U/C leg that subsequently doesn't retract properly and drain your only battery - then your up sh*t creek without a paddle!!