While having my original system I found no issues with the footwell woofers. Once I upgraded to the OEM HiFi system I still kept the original woofers and still had no issues. Then when I upgraded to the Top HiFi I decided to change the woofers for the proper ones (9192367), not because they needed it but because I thought it was best to.
Remember there are wiring differences between the different systems...
Standard stereo - The footwell woofers are wired in parallel with the door midrange for each side, left mid with left woofer and right mid with right woofer.
HiFi (676) - The footwell woofers are fed on their own single circuit, in parallel with each other, single feeding left and right.
Top HiFi (677) - The footwell woofers are fed on individual circuits of their own, one left and one right.
There are no aftermarket direct fit replacements for these, you'd have to make your own frames and then fit an appropriate speaker in that.
HTH
Remember there are wiring differences between the different systems...
Standard stereo - The footwell woofers are wired in parallel with the door midrange for each side, left mid with left woofer and right mid with right woofer.
HiFi (676) - The footwell woofers are fed on their own single circuit, in parallel with each other, single feeding left and right.
Top HiFi (677) - The footwell woofers are fed on individual circuits of their own, one left and one right.
There are no aftermarket direct fit replacements for these, you'd have to make your own frames and then fit an appropriate speaker in that.
HTH