Audio Systems: speaker upgrade, porsche 911, porsche 928

Question
I have a '97 porsche 911 cab with factory upgrade hi-fi. This features nokia speakers, I want to upgrade to a component 6.5 which will fit and use the factory grill. I also want to use the factory amp and head unit. If I can get a wiring schematic for this system( maybe from www.alldatadiy.com) Can you advise how to use current wiring and replace the terrible nokias with polkaudio. I think that this system has crossovers in the amp.

Answer
nice car buddy!  I took a porsche 928 for a spin a few times and I'll never forget it!

as for finding a diagram I dont know where I'd get one but I do know how to find out what's what and make it work without the diagram.   There may be a few hidden problems with just changing the speakers out.  first you should get a meter and remove one of the nokia woofers and measure its resistance to see if it's an 8 or 4 or 2 or 1 ohm speaker.  hopefully its 4 (read as 3.8 or so) if anything  else there will be problems. That's the first step.  let me know what the ohms are and we'll work on it from there.
the other thing you can do is use your meter to test the tweeter wires.  see if there's continuity between both of the tweeter wires against the woofer wires.  hopefully there is, if not the crossover needs to be found and measured and that's a whole other job!

let me know