XTZ 660 4BW
 

Hi !
I am owner of 660 Tenere ( 1996 ), model 4BW ( just 40 PS ) brought in Austria. The bike runs perfectely but it is slightely underpowered due to lack of power on full throttle. What do I have to do to turn it into 48 PS version? Is it difference just in carburation or maybe also in exhaust muffler?
Many thankes in advance,
AnteK