Subwoofer tweaks

Hi,

I have a Velodyne DD-10 and a friend recently let me borrow
a pair of brass spikes to try. I stuck them under the sub
and noticed an improvement. The sub sounded cleaner and
had better definition. I was wondering if anyone has
tried any other products (Aurios,cones, etc) that have made
an appreciable change (for the better I hope) on their sub.

Thanks