Stuck hugger bolts

Hi all, it's MarkJ here, fancied a name change after the server went tits up

I'm trying to get the hugger off the swingarm but it's having none of it, I haven't managed to get any of the four bolts off because it felt as though I was starting to ruin the head (these 3mm hex bolts are useless, why didn't Aprilia use the 4mm ones?)

The hugger is the CF one so I don't fancy breaking it to get at the threads, but this makes it awkward getting releasing fluid into the threads. It seems this is a fairly common problem, what is the best way to get these bolts out without having to drill them out? I left WD40 on the other night to try and loosen them but didn't work. Is it worth trying vinegar or diet coke to eat at the corrosion? Freeze & release any good? Can't use a blowtorch as I don't fancy setting fire to the hugger

The subframe is off so I could have a go with my manual impact driver, but these swingarms mark from the exhaust touching if you drop the bike, so would I end up putting a dint in the top of the swingarm doing this?

The bolt heads are still OK, however there is a bit of play when I put my 3mm allen key socket in. They are 3mm aren't they, not 3.5mm?

Cheers!

lol, I've just got all four out. Took me more than two hours though! Must have used a few gallons of boiling water too. Got the left one out just using the allen key socket, 2nd from left had to have a slot cut with a hacksaw and impact driver-ed out. 2nd from right was a right git and had to have a slot cut for the impact driver, then when that wore out (and one of my bits broke) I had to cut another at 90 degrees to get it out. One on the right rounded off but I managed to get it out fairly easy by hammering a torx head into it

Also, what grease should I use next time to stop this happening? I've got a load of copper grease, will this react with the aluminium?