I lowered my Betty 25mm on KW-V3 coilovers, it sagged a further 5mm after bedding in. It rarely scrapes on anything, occasionally the exhaust touches (I don't have any lips or skirts). It handles rather well, even on stock sway bars. There are some pics in my build thread if you are interested.

If you're not doing any track I wouldn't waste money on coilovers, get some good lowering springs (not King's) like Eibach, Bilstein etc...

Get in touch with John Fowler or Wilkinsons, they know they their stuff.

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Bye bye betty blue. Hello F6.