So for the 4V pre outs it is okay to use this connector : Receiver Wire Harness For select 1994-08 Chrysler, Land Rover, Mercedes, and Saab vehicles at Crutchfield.com

For the 2.5V I wouldn't want to use that one.. but instead use this? : http://www.ebay.com/itm/VOLKSWAGEN-Wire-Harness-Plugs-into-Factory-Harness-to-install-Stereo-Radio-/400344529418?pt=Motors_Car_Truck_Parts_Accessories&fits=Make%3AChrysler%7CModel%3ACrossfire&hash=item5d3664ba0a&vxp=mtr
Basically I want to upgrade my sound system (adding bluetooth, siriusXM, HD radio etc) without losing any sound or features from the original car!

Thank you so much!