Not got as far as I hoped with the 2 Landspeeders that are WIP this week - due to the hull gap problems which I am trying to fill but such is life.
I did manage to complete the magnetisation so here are a couple of photos to show where I fitted the magnets (marked with the green/blue circles).
The Typhoon missile boxes get 1 magnet each
the doors 1 each side for the Typhoon (in the small square recess on the door)
1 magnet under the chin and 1 on the chin weapon holder
1 magnet on the weapons triggers in the gunners hands
and finally 1 in the slot for the trigger on the multi melta and heavy bolter
9 magnets in total per speeder
I use 2mm x 1.5mm magnets which seem strong enough.