The first was replacing the piezo tweeter with an Eminence APT80. The cost of the APT80 was reasonable, but the components required for a pair of high-pass filter pushed the cost up. Looking back, it wasn't a worthwhile mod. The KSN1038 tweeter is actually a very good driver and there are various ways to tweak it to your taste. In fact, I'm using a pair of it as UHF in my JBLPro system.

The second mod was replacing the tweeter with a PSD2002 compression and crossing over at 1.6KHz. I called it my "Thermionic 2 PI" and it bumped the Towers up into the next class. Big improvement, but the cost for a pair of compression drivers, horns, and crossovers was a big investment. Unfortunately, my front baffle was cut exactly to plan and I did not have enough room to fit in the horns. The horns sat on top of the cabinet for several months. If your baffle can fit a pair of horns, this would be the mod I recommend.

The last mod was attaching Wayne's midrange horns on the Alpha10 to emulate the 8PI. That was a lot of fun too.

Gar.