The writing on the door panels over the speakers don't mean squat. Mine say "stereo" yet I have premium sound. However, you say you are using a Ford CD HU, right? Do a search on the forums and notice how many people have ditched the factory HU for an aftermaket piece. Seriously an aftermaket amp downstream from a factory HU is NOT a good idea. Plus, even the cheapest HU's from Crutchfield with decent power (15 watts RMS) will smoke the factory setup. It'll be the best $150 you've ever spent. I cannot stress enough how bad the factory CD player is; Kraco makes better sound.
If you do use a new HU then bypassing the amp is no problem, Crutchfield has everything you need ($15, free with a new HU; two days to your door). In the case of an aftermarket amp, just use the Crutchfield wiring harness to tie into the factory speaker harness and make the connection (input/output to the new amp) into the Crutchfield wires.
The hardest part of installing a new HU and bypassing the amp is fishing the Crutchfield harness through the back of the console to the new head unit--and even it is not that bad. Total time is less than an hour with proper tools (DIN) and very close attention to the wiring schematic.
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Matthew W. Campbell
www.bigmoneyracing.com------------------------