So this isn't really a mod, but I wasn't sure where else to post it. I built a Nautilus recently and decided to put together a 3P4T single-sided layout that can be used to mount two tri-color LED's. The LED's indicate which filter (HP/BP/LP) is being used. You can use one or two LED's; just leave one empty if you wish. The LED's will turn off when the pedal is bypassed if you follow the wiring diagram in the pdf I attached. This board is a tight fit and requires a modified drill layout. I included a layout that should work. If you drill potentiometer and switch holes a bit larger you should not have any problems. The 9VDC jack is also a tight fit so be sure that your jack will fit before drilling. These jacks are my personal favorite and will work perfect for this project:
http://www.newark.com/lumberg/1614-09/dc-power-connector-socket-500ma/dp/13M3783?in_merch=Popular%20Products&in_merch=Popular%20Products&MER=PPSO_N_C_EverywhereElse_None
And here is a pic from my build (PDF for this project can be downloaded below):
(http://imageshack.us/a/img51/333/photobw.jpg) (http://imageshack.us/photo/my-images/51/photobw.jpg/)