Amp wiring (wrong ohms?)

I just finished installing an amp and sub in my 90 civic hatch. The amp is a Pioneer GM X304 which is a 400watt 4 channel amp in which I am running bridged to a dual 4 ohm voice coil 12" sub. I have the sub wired so the load is 2 ohms. What I'm not sure of is what the amp is running bridged(Ohms). It seems to work fine and I'm happy with the performance of the two. My question is if the ohms were different (between the sub which is running at 2 ohms and the amp which I have no clue of) would I blow fuses, would it work at all or what risks am I taking? One other thing, I just came back from the local best buy and the installer told me that I'll need a capacitor to run the sub/amp combo. Like I said before it works just fine right now. SHOULD I BE CONCERENED?????????

Thanks....

you have all 4 channels of this amp bridged to one big super channel or you have it bridged to 2 bigger channels ? When you bridge 2 channels into 1 - each channel only "sees" half of the load, so if you have done option B above (you have one sub playing off of two bridged channels, and the other sub playing off of the other two bridged channels) and you have wired the subs for 2 ohms, then each amp channel only sees a 1ohm load. Some amps can handle it, some can't.

As for you salesman, sounds like he is doing his job .... trying to sell you something. A cap works for some car/stereo combos, doesn't for others. The thing caps do the best (when they work) is preventing the lights from dimming during loud passages.

Cool, thanks for the info. After further investigation I found the following statistics on the back of my amp:
30wx4@4 ohms
70wx2@4 ohms
Load Imp 2-8 ohms
Imput level 400 mV-2V
I guess I am running 2ohms out of the amp after all or am I mistaken? In case I forgot to mention earlier I'm running 2 channels bridged out of the 4 channels. Thanks.

2 ohms for each amp pair ...... meaning (if I understand you correctly) each amp channel is actually running a 1 ohm load