If you want power then you can always replace the assemblies to later model ones and have flippers that scare the shit out of the playfield plastics.  The ones on flash will always seem weak not matter what you do to them.

Mick - I installed flipper kits, bushings and flipper button contacts on Tony's Flash. The flippers were very powerful and responsive - in fact, a shot from the RHS flipper along the LHS guide, across the top of the lane guides, down the RHS, passing the the upper RHS flipper (Doh! - too late) and then SDTM !

Before I installed the new hardware, the ball JUST made it to the upper lanes.

I'll be replacing all the flipper hardware on future restores.