Just installed a Scale Sounds speaker and PBM upgrading this original Life-Like Proto BL2. I've used iPhone4 speakers until now and there is no comparison. Far better bass and rumble with the 567 ULT sound file. I used a dab of Goo contact cement to secure the custom-designed speaker. I also used copper beading tape to make a "trace" on the component tray for the common (blue wire) connections. Makes for a neater job.
As others have said, nice install and great idea. How do you insulate that common "rail" from the chassis? Also, does shortening the wires that much cause issues when getting to the drivetrain for maint. later on? I've been leaving some extra wire to in theory be able to take the tape off and move all the electronics out of the way a bit to allow taking the chassis weight off for access. Obviously it doesn't look as clean with the extra wire.
I have been struggling with the "common problem" on my last two installs. One of which is a LL P2K GP30. Had to chop the chassis weight done a fair amount, but it came out OK. But the copper beading would perhaps have helped. I'll keep that in mind. Ended up using the Ufit series speaker from SSS in the 17mm wide variety for the GP30. Also changed over to LED lights after I immediately fried the little original bulbs.
I also got the SD70Ace speaker from SSS and installed that in the loco I posted about originally. They both sound pretty darn good considering. My son just bought an Athearn RTR SD-40 with DCC and sound (we'll try to sell the DCC board), and it seems that SSS does have a deeper sound than the dual sugar cube included in the stock Athearn model (I can still run DC on the layout too, don't have DCC). On a side note, the sound from the RailPro equipped units is much more pleasing to the ear than the stock sounds from the Athearn SD40. They programmed some odd sounds into it when its moving. At idle it sounds OK, but there are some strange "squawks" etc when it moves, almost sounds like a squeaky wheel. Not really something I'd want to have on the layout all the time. Just my opinion, maybe those sounds are there for a proto reason.
Moderator edit: removed the pictures from the quote to prevent unnecessarily downloading the same pictures several times.