Yes, you'd need seperate power wires. It's not wise to piggy back them. Just get a distribution block. Is your current power wire large enough to carry enough current, however? If so, just use a dist block, and put the wire you're using now, to the block, then two wires coming out of it, going to your amps. You can do the same thing with your ground.
Your remote wire, can be piggybacked. However, a warning on this issue, your decks remote output isnt meant to deliver that much power. If you're using your remote out to power anything else (normally just a pair of amps wont cause any problems), I recomend getting a bosch relay for like $2 at an autoparts store, and use your remote to activate the relay, and use your 12v power source, to then go to your remote outs through the relay.
thanks alot seth, i have a 4awg amp kit, i think it should be good?now what type of amp would be good to power to 6.9's, jsut want something cheap, like how many watts would i need to make them sound better then jsut running off the headunit?
hmm. Well, how many watts RMS are your amps? That's pretty much what will decide of 4 AWG is sufficient or not.. Honestly, anything over 1000 watts RMS, I would upgrade to 0awg. There are several charts on various internet sites showing the length of wire/gauge current carrying capacity.