There's an excellent Pioneer "In the tyre" active subwoofer which I am about to buy - can't remember the number offhand - drops straight into the wheel dish of your spare, and fits either space saver or full tyre types. You can either leave it loose, or clamp it to the rim. It transmits nicely through the bodywork and sounds excellent; it has it's own amp and speaker built in and is very attractively priced; excellent wear and tear and shock treatment resistance. I have heard this unit wired to a 4ch/120 W channel setup, and it is excellent. With some creative connector work it is rapidly removable.

Recommended. If you want the model number, mail me here or off list.

One of the few remaining Mk1 owners... #00015