Whats your budget?
If your just after sound and you don't care to much about performance a cone filter and a decent cold air feed should suffice, K&N, piperx etc.
If you've got more cash you could look along the lines of an enclosed IK such as a Piperx Viper, BMC CDA or a ITG Maxogen which will give more sound and a performance gain without suffering with the problem of heatsoak which an open cone will.
A standard airbox with an ITG or green cotton panel filter combined with an uprated CAF ultimately gives the best gains per £, however it won't be that loud.