Could it possibly be the ticking from the fuel injectors? i have the 05 fz6 which has standard can at the min and can here the injectors ticking when its idiling.
lift your tank and have a listen to the back of the engine where they are, doesnt explain why the noise was louder at the manifold...
Drilling your exhaust isnt worth it only produces a very annoying hissing sound. My mate done it to his 06 fz6 thinking it would make it louder and it sounded s*#t.
you can remove the guts of the standard exhaust and weld tubes in to make straight thru but takes a bit of work and a dab hand...
Hi new to the forum and have problems with the bike. went out and started bike, started fine left it ticking over for about 25mins then engine trouble light come on when fan kicked in at (4 bars engine temp), fan stopped light went off. bike ran ok fan and engine trouble light back on fan stops...