I have used helicoil's in the past ....many years ago, for trying to repair motorcycle head to manifold joins (with varying results) ......the reason these two studs have given up is down to the manifold that I HAVE now decided not to use, the nuts all came off fine but due to the information I was given at time of purchase (about the 10mm clearance to steering column) and the lack of manipulation room, I had to remove the studs too to get the manifold on, that is when I found there was no clearance and it was rubbing ....so it was nuts and studs out to get the manifold out to heat up and persuade ......having taken it off four times now (each time the studs come out) I find that I have knackered two of them ........ The manifold is now clear and fits but I have now purchased a whifbitz 1st decat which is now on and will be staying that way ........I just hope to recoup some of the money I paid out for the 1st manifold now I have worked it into shape !!!