Clearance issue: this varies from car to car and the type of coilover you are fitting. The cars all vary to some degree with exactly how things line up relative to the body. Mine is quite a lot different to Dans for instance and from 1 side of the car to another. Best is to try fitting and then see what gives. Dont forget to lower the car fully down as the springs move away from the inner arch as the car lowers - a mistake i made cos i didnt realise itlol . To actually get enough clearance you might get away with a few smacks of a large hammer otherwise its cut and weld.
Strengthening: If the car is stripped out and you aren't rallying it,it will be so light that you can get away without any special strengthening around the rear turrets but you will need a good roll cage or strut brace to firm the area up.
If its not stripped out you will need to maybe plate and/or stitch weld in the area
IMO:D
