Am I way underpowering my subs

You will (and have) get a variety of different opinions. A lot of it depends on how realistic the manufacturers ratings on the subs and more importantly the amps are. Personally I am a big fan of extra wattage and keeping the gains low. That way you don't have any clipping, everything runs cool, and you are less likely to destroy an amp. I run my two 75W RMS subs off a 500 watt amp with the gains low. The amp stays reasonably cool even though it is in an enclosed space with a blanket and a tool set on top of it (not much space in my jeep) and sounds "cleaner" than the amp I originally purchased which was a closer match to the subs but had would cutout at high volumes after a while.

-Mike