Does anyone know what kind of Bolt this is? Its off a silencer inside a magnaflow muffler. I cant seem to take it out. I've tried a 7mm socket and it fits but when you put pressure on it starts to slip. Is it a 12 sided socket I need? or could it be an imperial size due to it being American?

Cheers

give it a good hard knock with a hammer and a suitable drift to shock it, then it will probably come undone fairly easily

Looks like a 12 point bolt head to me, as said above smack it with a hammer to shock it loose

Thanks for the suggestions, Would a screwdriver be suitable?

not really no, you need something solid like a piece of steel bar or a big heavy pin punch... you are likely to just damage the screwdriver tbh