Widboy, where do you live and where is your bike during the day? It’s probably a 5 minute fix.
Hi RolandJ
I’m really hoping to hear that from the mechanic this afternoon when I take the bike to the shop after work.
I live just behind mile end station and while at work the bike is on a loading bay between covent garden and the Strand (burleight street)
My Roadsitalia pipes were a bugger to fit on my Dorsoduro, but held firm after fitting and sounded ace.
Plus there was only a picture of what should have been the fitting instructions.
Which is more the shame it wasn’t done proper job first time, too many monkeys wielding the spanners perhaps :ermm:
Well I took it to the workshop and… Problem SOLVED, and yes it was a quick fix and it was a 2 min job, took it to the workshop, they checked it, they covered the exhaust end to check the size of the fumes leak (which was minimal), the tightended the bolts and checked again. They were both guys very attentive and nice.
What I think it happened is that when they installed it they did not tightened it properly (they should´ve paid more attention perhaps), the exhaust heat made the metal expand and then once it cooled down the little gap appeared. Anyway, I´m very happy it´s solved.
A big THANK YOU to all of you for the advice and dedicated poetry. It was really appreciated.
Case closed! Cheers!!! 
Excellent Now get to enjoying your CBF500. Awesome bikes they are!
It’s probably not that it was leaking to start with, and more that stuff’s settled in in the interim. It would have been good for the mechanic to have explicitly said “it might start leaking as it settles in, bring it round and I’ll nip it back up again”, but I’m not convinced this one was a problem that necessarily ought to have been caught at initial installation. Unless by ‘proper job’ you mean ‘smother it in silicone’…