Sundown currently offers a pole cap shorting ring - it does NOT do the same thing as adding a slug of neo - as aluminum is non-ferrous.
Coincidentally, the upcoming NSv3's offer an entire pole sleeve, which requires a bit bigger motor slug to retain strength (as widening the gap for the sleeve decreased BL a bit).

Quote Originally Posted by DDtC View Post
Its the same thing Sundown does but instead of aluminum its neo. There was a drop in test done, Distortion was decereased at full excursion, and the amp clamped a lower imp. Thats how people are gaining close to 2db with it. I'm looking at super charging my set before I swap amps and I'll do a before and after.