Was in the process of trying to remove exhaust studs on the downstream cat for my 1998 maxima.
tried heat, extractor bolts, breaker bar, impact etc. won’t budge.
Any suggestions? There is no nut on the other side of the stud so I’m assuming It is pressed in and the bolt is splined, but it’s also pretty much rust welded together.

 

Cut the bolts with an angle grinder.

 

ive seen (and dealt with) worse.

torch until the flange is glowing, penetrating oil, wash/rinse/repeat a couple times. then torch, spray, remove.

the oil will likely flame when sprayed so be aware.

 

These three videos gave me some good ideas a while back:

 

I've experience stuck bolt on exhaust, generally best method I've heard is spray pb blaster and let it soak for about ten minutes and then add some heat since it help expand metal and use a breaker bar, since hand wrench will not do it. If you're working under the car laying down, best method is have impact gun since not everyone has access to a car lift which case most of us have the car jacked up and crawling with a creeper.

 

What slvr2K and Fanatic said … be patient.

It may take 2 or 3 applications and attempts but it should work.