your tricks to remove exhaust nuts at the manifold

I tried my usual recipe for success - multiple days with kroil, heat and candle wax wicked in.  No go this time.  The impact battery was low so I don't think I was getting as much force as I could.  Before I try this again, any other tricks to try?

If you have access to a torch or even better and induction heater now would be the time to use it. If a little beat didn't work try more heat. 
Alternatively, cut the bolt off, then work with the stud once you have the manifold out of the way? 

What kind of access do you have? 

Heat and more heat ussually works, but we are talking oxy-acetylene levels. 

Can you get a air chisel in there? Spliting the nut worked for me recently, but you have to be able to deal with the split nut.

I have a "nut splitter" tool that clamps on to a nut and tightens a tooth into the side to split the nut. Works great when the acces is available but that is more the exception than the rule.

Don't break the stud. That low power rattle gun going backwards and forwards will contribute to the thing coming off eventually. I get real patient when I don't want to damage a stud. Heat, lubricant, vibration and reversing loads usually work, but I am talking a day to a week for results.

NOHOME said:

What kind of access do you have? 

Heat and more heat ussually works, but we are talking oxy-acetylene levels. 

Can you get a air chisel in there? Spliting the nut worked for me recently, but you have to be able to deal with the split nut.

I have a "nut splitter" tool that clamps on to a nut and tightens a tooth into the side to split the nut. Works great when the acces is available but that is more the exception than the rule.

Don't break the stud. That low power rattle gun going backwards and forwards will contribute to the thing coming off eventually. I get real patient when I don't want to damage a stud. Heat, lubricant, vibration and reversing loads usually work, but I am talking a day to a week for results.

That last bit.....  I can feel that in my bones.

It's better to work on a stuck fastener at your leisure than it is to drill and tap a broken stud.

First thing I do is clean loose rust off the stud.  If heat is an option use it, but a good penetrating fluid and some time and more heat usually work.  I have also tried tightening the nut a little and putting more fluid in.  

I have a MAPP torch and enough access to clearly see the fasteners and aim the torch right on the nuts so I'm happy with this.  I'm happy to be patient.  I'll add reversing to the repertoire.  Plan is to remove the engine so I'll have a decent chance to fix it later but would rather not have to.  

Turn that torch up as high as it will go.

Quenching the heated fastener is another accepted method.  Not a method that I use but I could make an argument for it disrupting the oxide layer that is making your life miserable. 

It all depends on the fastener.  If it is a stainless nut, heat makes things worse.  Gentle but persuasive bapping with an air powered impact is the best way for those.   No long squeeze of the trigger, just bap bap bap.  Alternate tightening and loosening.  When it starts to move, keep the staccato bapping until it is off.

If it is not a stainless fastener, make the nut orange before you try to move it.