Has anyone used the RF 3Sixty.1 or .2 in their S2K? I'm thinking of just keeping the stock head unit, running the 3Sixty, upgrade the front components, and toss in a shallow RF sub in the trunk... has anyone had any experience with it? My local installer found that in his experience, a stock HU with the 3Sixty and an amp is better than an Alpine and an amp...

 

I would go to a different installer . . . and get an Alpine

 

Those units are designed to integrate into more complex stock/factory stereo systems where replacing the factory radio is not a simple task, for example a car with built-in nav to the audio system or video system.
The radio in the S is a cheap piece that is extremely easy to replace. Get a new deck and separate amplification for the speakers, that would be wasted in the S, IMHO.