Get a new headunit with an amp or sub out line, and voila. That's all I had to do. I got a Sony headunit, an adapter to hook the Mach 460 wiring harness up to that specific headunit, and ran some RCA cables from the amp-out line on the back of the radio to the amp. I have the subs in the trunk, with the amp between the subs and back seat. It's actually not hard at all to do. But you'll still have to run a power wire from the battery to the amp also.
Or you could do what I did and get a line out converter, and run it off the rear speaker wires. You will have to run a power line from the battery and a ground, but you can still use the factory stereo. I have done that in mine and it sounds great!
Or you could do what I did and get a line out converter, and run it off the rear speaker wires. You will have to run a power line from the battery and a ground, but you can still use the factory stereo. I have done that in mine and it sounds great!