Originally Posted by broken-wrangler
Yes I know what ohms are. You can take a 4 ohm sub and take it down to two ohms by bridging either side.
That is a simplified idea of it, yes. To nitpick your original question you don't increase voltage by changing resistance, you change the current flow :P
The factory sub is a 2ohm DVC. I would suspect it can handle more power but the problem is the factory amp. The amp has two channels that feed the sub's two coils. If you bridge them and run off one channel at 1ohm you will most likely destroy the factory amp. If you tried to bridge the channels you are likely to destroy it as well.
The factory amp, being OEM, doesn't have any real published stats on bridgability or ohm stability. The sub's power rating isn't published either for the same reasons. Top it off with the fact the factory amp rolls off the very low end (Can't hear under 30hz when I had my factory setup) and you have quite a few things stacked against good bass.
The easiest solution is to either gut the factory system or get something that does line level conversion, a bass restorer, and a new amp/sub.