i find some brute force and ignorance works wounders :D

I had never really been a believer in wd40 but I think it really did help.
Had a go earlier with a little bit of hammering and I got a few of them off fairly easy, until the torx bit damaged.
I think the the most important part is cleaning out the head of the bolt to ensure a good grip and avoid damaging the head.

Its at times like this that quality tools come in to play as well . Once the tools knarl up they chew the bolt and its game over, then its grinder and chisel time:o

Bob