Quart used to be the standard in car audio. They were sold out to a Taiwanese company a few years back. Before that happened, I rounded up Premium Series drivers in each size so I could accommodate any future installs. One set was used in my MINI for about a year, the others have been gathering dust.

$175 PCE-216 component set - 160mm + 25mm + crossover (6.5" components)
$150 PCE-213 component set - 130mm + 25mm + crossover (5.25" components)
$100 PWE100 midrange kit - 100mm midranges (4") - brand new

Each set has associated hardware.....install parts, spacers, grilles, flush mount tweeter cups, center post tweeter mounts (for coaxial use) and of course the crossovers.

I also have an RXE-164 Midbass crossover (stereo). This allows you to use the 6.5's as midbass and mount the tweeters in the 4" or 5.25" and use that crossover and have a nice three-way system (like in the front of an R56 MINI. New, never used.

I have adaptors made to fit the front of the R53 MINI (included) for the PCE-216 set.

On to pics...PM me with any interest please.