Go to Autozone and pick up a set of Energy suspension bumpstops. They're only about $12.
These...
I used 1 1/2" OD 1/4" wall tubing and cut to length per side, welded a washer to the bottom and tacked the nut for the bumpstop centered over the hole so once I welded the top end of the tubing to the bottom of the coil tower I'd never have to remove it to replace or adjust the rubber bumpstop. They hold up pretty darn good.