I've noticed several posts about DDin installs in caymans and boxsters in this forum, especially about the cars with BOSE in them. I won't bother you with advertising, besides this lol, but I live in the Dallas area and I'ld be glad to install anything you want in Caymans or Boxsters.
Bose is not a problem. I just did an AVIC D3 install on a Cayman, with all factory speakers retained except center channell, which could be retained with enough work, no rewiring required. The BOSE amp of course cannot be retained, although I'll leave it in for the computer's sake. You will need a new amp, especially if you care to retain the door subs as few radios are going to like 1Ohm speakers. New speakers are fine, just not required.
I can guarantee that it will all work correctly. I can do the Handbrake Bypass on almost any double din. I can add bluetooth ipod, etc, for little to no extra cost.
And, our client was a member of your forum, so you can get feedback. I also took pictures for reference.
I can't promise I'll be THE cheapest deal. But I can promise I'll be right there with the cheapest and way under a shops price, and I can promise I know what I'm doing in your car.
to contact me, email firstname.lastname@example.org or call 214 783 8592.
I can help you find the dash kits and harnesses if needed too, or pick out a particular head unit or amp.