Have a cb400 sf. Have my a2 test in a couple weeks and pretty sure it needs restricting. Has anyone used something like this

http://www.ebay.ie/itm/Honda-CB-400-…-/221515122387

and done it themselves? The listing says the cert is ok with the RSA but not sure whether to believe it or not. Any advice? Or anyone selling a restrictor with a cert for a cb400 sf?