I just bought a brand new 2007 X3. Only problem is no one seem to be able to tell me the speaker size dimensions and some other space constraints for a good stereo installation.
I take delivery next week.

My current vehicle has Boston Acoustic Pro 60 in the front of my car ( 6" components) and Boston Acoustic S65RC ( 6" co-axials) in the back with two Alpine Amps MRP-350 and MRP-250 as well as an enclosed 12" sub.

I was thinking of mounting the amps under the rear seat (they are not heated) since they use convection cooling and have withstood high temperatures before.

I would really like to re-purpose the speakers since they are not cheap and the best sounding seperates I have found in ages. If not some hi end speakers that will fit?

Can anyone tell me of any experience, knowledge or suggestions for placement that will keep the interior as close to its original state?

I dont mind doing some modifications under the skin. The idea is to keep it looking stock from the outside looking in.

I couldn't tell you off top of my head, but if you send me a PM, I can help with professional installation. We would have to take the car apart an do some measuring.