Amplifier heat?

[reedal]

The subs were both in parallel I'm pretty certain. The amp is rated to 900 watts peak and 450 rms for 4 ohms under 1 sub. The subs are rated 600 rms and 2000 peak. It's becoming apparent that I need to get a larger amplifier. Also how or where can I find out what my Amps optimal ohm rating is?

Since I'm assuming your statement of "450rms for 4ohms under 1 sub" is where the amps says mono-bridged, that's what your amps optimal ohm rating is if you're bridging the amp. 4ohms. So if you have two D4 subs, you need to wire them in series parallel as shown in the link http://www.the12volt.com/caraudio/woofer_configurationsm.asp?Q=2&I=42#results

And just because you wired it that way doesn't mean it's what it actually is, so take your DMM and double check the reading.

I would suggest a more powerful amplifier. You can get a 1.2kW-1.5kW amp for a decent price. But if you don't already have one, you should get an oscilloscope or DD-1 to help set your gains properly.