i recently picked up an SR104, and desperately need a fully functional grill for it, and not one of the crappy cosmetic ones. this is going in a little convertible, and i haul all kinds of crap in there with me, so i cant risk having a loose screw driver or something like that go flying and punch a hole in the sub.
would something like these JL grills work? http://www.sonicelectronix.com/item_...o-SGRU-10.html
if that doesnt work, i might go with a DB grill and wrap cloth over it.
If you need a grill, and need the protection. Go with either the DB, or MM grill. This will however require you to get an MDF spacer ring, due to clearence issues with out it. You can get them via ebay, or amazon. Do a google search for it as well.
There is also a thread on here were someone used an MDF spacer, and the MM grill. I dont like the JL audio ones cause it does not offer enough coverage. I would also venture to say that if you use the spacre you might be able to get away with using a waffle style grill, but you might not have enough clearence when the sub is pushing.