Yeah, 15ft should be plenty for you. I also think that 1 ga cable is overkill for your setup, not to mention more expensive. You should be just fine with a single 4 ga power cable from the battery. I run 2 DEI 1100 D's, and a DEI 600 on one 4 gauge without any probs. I would say 4 gauge is a minimum though. I also like to run a separate ground cable from the neg of the batt to the fender, as another ground point, to help ground the chassis a bit better. Be sure to use good, clean, bare metal grounds, and use ring terminals that you bolt to the car. Good grounds are overlooked quite often..and always use the same gauge ground as power cable.

13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)