Quoted from delt31:Take some video of the eyes of possible interested to see if that's worth it. I was thinking speaker upgrade too what did you go for?
There's video on the Bony Beast mod thread - the pupils go back and forth, "looking around", and blink. it doesn't interact with the game but it's active enough it doesn't really matter
for the speaker upgrade, I rolled my own - added an L-Pad and a new 8" 4ohm high efficiency speaker (I think it was $25?) and 2 brand new 2-way 5.25" backbox speakers which were $25 a pair or something.
If I were to do it again, I'd absolutely skip the backbox speaker upgrade; it just doesn't matter. The stock speakers are "ok" which is all that is needed for the stock music in the game. were I upgrading to a PinSound and adding my own music and callouts, it would be worth it.
The woofer is very important (make sure it's 4ohm on DCS and WPC95 games!!) but the absolute critical thing is the L-Pad. Flipper Fidelity and Pinball Pro include this (it's the little 'volume control' thing). This is the secret sauce IMO. Adds bass (as much as you want) where before there was so almost none to be found.
This game had horribly tinny sound before, zero bass, the backbox speakers would hurt your head if it was up too loud, and the cab speaker was basically not doing anything. Now, it is much improved. My particular game (to my horror, as I missed it when I originally got it) has a Rottendog A/V board, and that may(?) have something to do with the weak sound. I don't know - but it is killer now.