Depends how uch you want to spend... Take a look at
http://www.svraceshop.com/ (this is the second time I've plugged them today, I'm not on commission!), Clayton there does various levels of rebuild to GSXR shocks... Not tried one (I have better
) but he gets amazing word of mouth on SV Rider...
But if you want cheap, concensus is 636 or ZX10R. SRAD works too but the shocks are getting old, and they weren't long lived to start with- much easier to find a nice 636 shock.