rockford fosgate

is your 15in sub a 900rms max?? usually 15in subs are about 1000watts max... and the word being max... you can run a 900 watt max sun with 400 watts easily.... its not a good idea to run your speakers at max output... the rule is that you run your speakers at HALFof the RMS max!!!

the problem with this is running the amp at 3 ohms.  In a bridge state the amp can run at 4 ohms max.    Over time your amp will fry from putting out to much power.  So just be careful about that

If my calculations are correct, dropping the amp to 3 Ohms would result in about 1200w output. As for dropping the Ohms below 4 when bridged, not a good idea, but probably not dangerous. The amp should go into thermal shutdown mode, & shut itself off, if it's being overpowered. If this happens, rewire it back to how it was. It shouldn't fry just from trying it, but then again, don't take the chance if you can't afford to replace it.