Without doubt the hardest part was getting the tender open to install the speaker!!
Simon Modelling CB&Q and Wabash See my slowly evolving layout on my picturetrail site http://www.picturetrail.com/simontrains and our videos at http://www.youtube.com/user/MrCrispybake?feature=mhum
We put a Tsunami in mine but it all depends on WHICH big boy you have. Red Box, no problem Older than that the motor COULD be a problem.
The hardest job was the sound unit.
If it's DC powered, why install a decoder?
If you are running DCC, a TCS T-1 or any similarly sized or smaller decoder will fit into the boiler on top of the motor.
I have a DC powered Rivarossi Big Boy, suggestions for DCC decoder to upgrade the loco please.