IMO for that price look for good used options ebay, breakers etc as the quality will just not be there or wait and budget for around £700
these BC's give some damping options but I have never used them as a product so cannot comment on the ride quality
http://www.scoobyparts.com/suspension/bc-racing/bc-racing-coil-over-set-new-age
and here with some optional adjustment
http://www.scoobyworld.co.uk/catalog/product_info.php?cPath=39_268&products_id=1549
and the actual website gives an extra low option on the RA
http://www.bc-racing.co.uk/applications/subaru-coilovers/subaru-impreza-gdb-00-07-not-sti-05/br-series-coilover-type-ra-4.html