I take my MIG welder and lay a fat spot weld on those broke exhaust bolts. The weld will not stick to the head and it hurts nothing. Let the first fat spot weld cool and do another right on top of the first. Repeat the process till there is enough past the head surface to grab with vice grips. The heating and cooling of doing the series of spot weld help crack the corrosion seizing the bolt too.
Oil the crap out of it with your fav penetrating oil and start working it back and forth to use the threads to grind up the crud in there. Youll soon see its getting easier and easier to move the stud...then slowly start removing it ..work back and forth and be patient.
MY BIKES..1977 GS 750 B, 1978 GS 1000 C(X2)
1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550
NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.
I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.