It seems more pronounced when I'm stopped or accelerating, I can't really tell at speed, the scorpion zorsts are too loud!

The bike has done about 13500 miles now. It's been well maintained; always serviced on time and has had lots of love in the past, nothing I have indicates the CCT's have been replaced but the previous owner suggested they were done before they bought the bike.
If I am looking at a new front and rear CCTs how much damage is it going to do to the wallet? I assume the labour is the expensive part, what's the going rate. Is there anything else I should get done at the same time?
Cheers
Matt