seized and threaded bolts in dc5 catalytic converter

[BLV-27J]

the bolts that connect to the exhaust on the catalytic converter wont come out. i have tried wd40, freeze release, another brand on penetrating spray, bernzomatic blowtorch to heat up the bolts, and neither will budge. im thinking im going to have to cut them off some how because im installing a new exhaust, but is there any other way to get these bolts out before i try cut them out with a dremel? thanks

SORRY I DONT THINK THEYRE THREADED I MEANT THE TOP OF THE BOLTS ARE ROUNDED-

[Super-DA9]

when this happened to me, I drenched the things in WD40, wiped the heads clean, and clamped on a set of clamping vice-grips as hard as I could, and after many attempts to turn them they finally came loose. for the one that didn't i got a socket that was 1mm smaller and bashed it on with a hammer, then connected a breaker bar to it and turned.

[potato]

There are plenty of tools for taking off rounded bolts. If you're in melbourne, shoot me a PM and I'll lend you mine.

[V73C]

Just buy new bolts and cut it. does it look old and crusty ?