2ohm and 4 ohm are the same thing, the only variation is the convenience in wiring configurations. A Dual 2 ohm speaker can be wired to present a 1 ohm or a 4 ohm load on the amplifier. Commonly used for single woofer set-ups. A Dual 4-ohm speaker can be wired to 2-ohms for 8-ohms. If you're getting a pair of Dual 4-ohm speakers, they can be wired together, to present a 1-ohm load which is what I'd recommend in your situation. Getting Dual 4-ohm voice coils.
Also, here is a link to a great deal on some of their b-stock subs. The SA-15s are available in the D4 for $170 shipped, I'd jump on it //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
Used, B-Stock, Refurbished Amps, and MISC - SSA Car Audio Forum
What subs with a similar RMS rating are cheaper? Are they sh
itty subs? SA's are known for being a rather affordable line. Keep in mind that while rated for 600w RMS, that is very conservative, and they are known to take power levels in excess of 1,000w very easily. For example, I feed my SINGLE SA-10, 1200w for daily usage and don't have a problem. If it helps, think of it as a 1000w sub. Also, another similar and good quality sub line to keep in mind is, Obsidian Audio. Very similar to the Sundown series, and the designer of the SA's collaborated to make the Obsidian drivers. These are also known to take well over 1,000w daily.
Obsidian Car Audio
They are similar to the Sundowns, but known to be a bit more SQ oriented.
