98 Mach system replacing with aftermarket I have questions

[fast _shelby]

I am getting ready to buy a Sony MEX-BT5700U head unit. I have heard the factory radio has the amp built in for the factory sub. Does this mean I will have to buy a aftermarket amplifier to run the factory sub?? I have to replace the sub with a aftermarket sub also. I heard 8" subs fit in no problem.
Thinking of buying everything from Crutchfield.

Thanks in advance.

 

[Joe Dirt]

The sub is run from a separate amp attached to the sub enclosure. The amp for the radio only runs the door speakers...

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