Hi mate, that setup realy does sound the absolute nuts!!!!! So much so, thinking of going for the rc racing group n back box you posted up before.
A few questions tho... you say 'straight centre pipe'. Does this mean your man removed the standard centre pipe with silencer that comes from the factory, and replaced with a straight through centre pipe? As I see rc racing sell both the unsilenced centre pipe and one with a silcencer. Would be excellent if the gr n back box could go straight onto standard silenced centre pipe and still produce that magnificent sound.