Use replacements that fit in the holes. The door speaker holes can accommodate a standard 6 1/2" driver. I've fitted JVC replacements in my SE, which cost almost nothing compared to the HK stuff.
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The sub is more of a problem, as I suspect the driver isn't available without the enclosure, and the enclosure is silly money.
I suspect yoi could find a replacement driver that fits the enclosure, but it won't work as well as the original.
My SE didn't come with the HK system, so I added a subwoofer to my FL1 by installing a large sub driver into the cubby and making a wooden baffle board for it. It sounds amazing, but does make the cubby useless for storing the jack.
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