Bobkat
1979 x1/9
That's about what we've been referring to as "kick panel" speakers. The ones you pictured appear to be larger, deeper speakers that stick out more. That might be too intrusive in the tight X1/9 footwells?
Companies make pre-fitted kick panel replacements like that for certain cars. Obviously not for a X1/9, but there are also some universal ones that might make the install easier:
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I wounder if a good 4 inch driver in a kickplate box and a remote tweeter would be better. There is not a lot of room under there.