Is it okay to swap porsche head unit for aftermarket?

I just had mine done a couple weeks ago, it took like 4 hours for them to install it because they had to hardwire it to an "oem converter"(got it from crutchfield) then hardwire it to the car. It works fine, but yes, the horn does chirp(which wire do you ground?????) Sounds awesome, but Porsche apparently doesnt give a rip about aftermarket stuff because well... its a Porsche. (And I wish more people could get Porsches because I see about 50 billion hondas around and the parts for that car are dirt cheap, I wish I could get a complete turbo setup for like 2 grand, or a $500 bodykit.)