Removing Studs linking Exhaust Manifold

Good evening, I’ve been working on my E90 for sometime now and over the last couple days have been attempting to do my centre support bearing.

Living in Ontario it’s cold as fuck, and with all the road salt we get lots of rust and corrosion. I’ve managed to remove a couple corroded bolts and screws but it seems like people always have trouble with the 4 studs linking the exhaust, myself included.

Either the bolts are rounded or have molded into a glob of metal. What is the best way to attack this? Drill it out? I can barely get a socket around any of the nuts, not like they’re moving anyways. I’ve checked YouTube but as a kid with not much experience I’m wondering if anyone has any suggestions, any support is greatly appreciated.