I am pushing a C310D2 Memphis sub with a Punch-500 amp at the moment.

How good are the Sundown Audio Subs? Would be looking at a Single 12', New Box, and Maybe new amp?

http://www.sundownaudio.com/index.php/products/subwoofers/item/e-series.html?category_id=2

e12 or 15 would be nice for that amp if you don't want to buy a new one.

http://www.sonicelectronix.com/item_63976_Pioneer-GM-D8601.html from like amazon if you want to get 1 e series now and add another one later.

Ya i would like to stay away from buying a new one

I'd get the E12, Any good boxes out there for it?

What's the problem with the Memphis? a 12" should do just fine. If you want a Sundown go with the E if only pushing 500rms. Also the 12's like a good 2.0ft^3 to get down and nasty.

no problem what so ever but im just wanting somthing a bit deeper.

The amp is actually pushing 6xx, alright i'll keep that in mind. i'll be looking around for boxes