what is my wattage

i am unclear of the advatages of bridging my amp...i have a jl audio 1000/1 and 3 jl audio 12w6s....the amp is rated at 1000 W RMS @ 1.5 ohm - 4 ohm.....does the watts go up when you run your subs at a lower ohm or will it make a difference with my amp.....my subs a rated at 400 watts Thermal Power Handling.... does this mean 400 watts RMS?   I want to give my subs full power so will my amp run them at there full power or should i get anouther amp and run 2 or them off one amp and 1 off anouther amp like there 500/1.....please help me clear this up.....also i know how ohms law works but i am not sure about watts and RMS, if someone could clear this up for me.....thanks  

Or better yet, get your alternator upgraded to work with it.

You'll want at least 155 amp alternator to let this system hit hard continuously. Batteries will give you hard hits too, but only for a limited time. For example, say you have an 80 amp alternator and 665 CCA battery (this is average for stock setups) you'll be able to hit for 15 seconds at full power before your battery becomes drained and deep cycles. After that it can only go for about 10 seconds and the battery might only be able to get to 9-10 volts. This is assuming you also get the 500/1 as well.

If you run without the 500/1 then upgrade to at least 125 amp alternator. Running average factory setup without the 500/1 will give you about 17-18 seconds at full power before deep cycle starts to set in.

Good Luck!