"letting the sound out" of an Atlas Trainman GP38-2

[IDRick]

I love my atlas locomotive, it is such a smooth runner and has modest detail which makes handling much easier!  Installing a Railpro LM-3 appears straightforward in this locomotive.  I have found example installs and all show installing the speaker over the rear truck.  Since the fans are solid, the installers are boring a hole through the rear weight to provide sound access out through the bottom of the loco.  See photos 6 and 7 in the link below.

https://www.soundtraxx.com/documents/appnotes/atl_emdgp38-2.pdf

Are there any specifics I need to know relative to boring through the rear weight?  I am wondering if sound quality varies depending on the shape and dimensions of the hole?  I am leaning toward a single rectangular cube speaker.  A larger speaker may also fit. Thanks for any assistance!

[BruceRogers]

There should be no problems boring through the weight that I can see. After seeing this post I think I might add some modules to my Atlas GP39-2s