HELP- removal of header from exhaust system
 

I think I have a leak in the joint between where the header (after the Cat) attaches to the start of the exhaust pipes. The nuts and bolts are badly rusted away.

RealOEM.com shows bolts/nuts but also looks like the original bolts are tacked onto the header (which what I think mine are). Has anyone ever broken that stud out to replaces them? Drilled out?
Searching if any other DIY have done it or should I look for a muffler shop?
The rusted photos are my car, other photo is someone selling on Ebay to show the studs.

THNAKS!

They look like bolts .pb blast is what I use. I leave it around an hour or more, then gently try to take them out. good luck

mine are WAY past penetrating oil, one of the nuts was completely rotted away.
They are pressed in studs. (attached photo of what they look like new)
I took it to my local independent muffler shop and bargained with them to get them out and new bolts (non pressed regular bolts) for $100.
They used a torch and air chisel.
I would have had to drill them out.
I will replace them with stainless bolts/nuts in the spring

I was going to say they are pressed in bolts, like some wheel studs. Banging them out when they break or stripped is not fun let me tell you.

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