I haven't had experience of kleeman but I've just fitted a eurocharged supercharger pulley and remap to my C32 AMG......quite a bit cheeper than kleeman and gave mine a 50hp 50lbft increase....
Blimey......just investigated the pulley....£1700 plus vat....eurocharged are £650 all in!! Not sure kleemann will make it worth over a grand more when you come to sell! From experience any mods hit resale unless the person wants a modded car to save them the future hassle!