Failed Mot, downpipe question about replacement

[Dead Eye]

Most change the nut only and try to clean up the stud. If the studs are in good condition you may be able to remove them and replace them, but in my opinion its not worth the hassle as if you snap one then its basically an engine out job to get someone to drill it out and re-tap the head...

Just take it steady and don't apply too much torque, but if you are cutting the nuts off then you should have less of a problem. I'd suggest you start spraying them liberally with penetrating fluid like WD40 now and give it a few days to soak in. First set I did practically fell off without any drama... the second time (different bike) every single stud snapped bar one and 2 snapped off flush with the head