i was never a big fan of using the transformer solenoid voltage high tap. sometimes its called a low line tap if your 120vac is lower than normal. if I=E/R (basic ohm's law) than a higher voltage = higher current flow thru-out the machine = higher arcing of switch contacts. flipper power can be improved by using dotted or juicy flipper coils (same part# but stronger) availible from PBR. i played a small flipper machine with these coils installed and it made for faster fun play. gottlieb EMS really never got into dc pop bumpers or slingshots and were all ac coils. i read somewhere that un-winding and removing up to 4 layers of windings will increase its strength. i have tried this by un-winding 3 layers and was happy with the results, close to the strength of a dc coil. don't get greedy and try to remove more than 4 layers from a coil, it will be a short and the coil is ruined. since dc coils are stronger already i didnt try this on those. any questions on this please ask. more EM mods to follow. if you have a favorite EM mod please post it.