[Hellz]

i had 2 botls broke off my 03 H2 within the first few months of buying it in 2008.

i was still covered by a extended warranty, so they fixed it.. but honestly i wouldnt hesitate at all and do it myslef if i needed to fix broken bolts again.

just have to disconenct the exhaust
unbolt the head
get in there and get the old bolt out
put back together

ya i make it sound alot easier than it prolly is, but your not replacing any gaskets. while your at it, you can replace the bolts to some aftermarket ones that will hold up better.

if your lucky, and you have some of the bolt sticking out, you dont even need to disassemble the head and exhaust.

get some WD40, vice gripes and some muscle.

maybe a torch to heat things up a little to help break the bolt out.

chances are tho, the bolt is broken flush to the head, but never know.

as for how bad it can get...

well, assuming it is just 1 bolt right now..
eventually with the hot cold expansion, it will snap a 2nd, if it hasnt already
then add in vibration with the hot cold expansion.
by the time the 3rd bolt is broken, im sure the sound will annoy the hell out of you, and it may not go away once the gasket heats up. there will be too much of a gap between the head and the header. so you will hear more of a exchaust leak instead of the ticking sound.

worst case, you break all the bolts, and it is only held next to the manifold by the exhaust header. im sure you will notice the burning smell from all the wires cooking before there is actually a fire.. but.... again i would say that is extreme worst case.

i would also say there is a chance of warping the header, and possibly the head too if left long enough. ( i would think this would take a year or 2.. not days or months) but then again, i wouldnt even call myself a backyard mechanic.. i just fix my own stuff.