First of all, thanks for the replies guys, appreciate it.
The heat shield thing sounds pretty good, but I also got a brand new short shifter fitted to my car a few months back, so yeh, that may be the problem.
I might have a look to see if I do have this "heat shield" for my cat converter, but I most likely will be cbf.
But yeah, it sounds pretty troublesome to look into and if it is a "normal" problem/issue among the u12s then that's the way it is. I thought it might have been a major problem.
All cool.
Cheers guys, thanks again.