blitz nur spec R vs blitz nur backbox
 

Hi would like to know if the blitz nur spec r system 3'' is any louder than the blitz backbox that tapers down to 2.5'' asuming middle and downpipe are decatted.

think they both taper down to the standard bore size, the nur spec r goes down to standard size where it fits onto the down pipe, not sure about the nur backbox?

this is for the classic

what about sound difference is ther any.