Quoted from Phbooms:Shaker motor is my favorite mod i added. Pinblades and speaker grill lights i added also but there just cosmetic and not needed. Honestly havent seen any addon playfield mods that i like or feel look worth buying.
Did you use the Stern OEM shaker motor or one of the other kits out there? The Stern model may be overpriced, but I'm concerned about warranty headaches.