Since you're working with a top-loaded guitar like the Silo, I would highly recommend soldering in some leads on the tone pot and using alligator clips to experiment with different tone cap values.
The general idea is higher value caps have a more drastic treble roll-off than lower-value caps.
Get one of those Radio Shack variety packs and find a value that works for you. If you're so inclined, you can shell out more bucks for a higher quality brand of cap.