Check out flemworld.com for schematics on both Mach systems. Their information states that the output on the amps are 4 ohms. When you pull the stock speakers out check on the magnet for the ohm rating and then stay in that range for the speakers.

 

the speakers that i pulled from the rear deck did not have a ohms rating on the magnet. that did not concern me at the time cuz i assumed that it would be 4 ohms and replacing them would work out great. it was when the amps started shutting down that i consulted the forums and seen that the mach systems had a different ohms rating.
ford really pulled a fast one on me with the mach system. i installed all new speakers in a eclipse running off the stock amps and the improvement was amazing. i assumed i would get the same results from my stang.
none the less, im sure there is a solution other replacing everything i just havent had time to mess with it lately

 

http://www.partsexpress.com/pe/showd...number=019-015 imma try wiring one of these in paralell with the aftermarket speakers to acheive a 2 ohm load and see what happens