I used 220 uF, 35V electrolytic caps to do the mod. I have 100v in stock and they will work just fine, although just a bit bigger. After installing one side, I sat and listened to a bunch of songs and decided the this mod leaves a little gap in the upper mid-base. I finished the job and got a "thumbs up" from the wife. (The ultimate approval).
But, it sounds MUCH better!