How to get seized bolt out of V-band clamp that holds header to cat? *pics*

Heat the nut, then support the nut in a vice. Use your vice-grips to turn the bolt. If it doesn't move, then try more heat cycles until you get it out. Also, some penetrating fluid will help.

 

I was going to suggest putting two nuts on the open end, but too late.

 

File a little flat side into the round part that receives the bolt. Put that in a vise. Heat it cherry red, use a vise grip to turn it loose. If that does not work, cut off the bolt flush and drill it out. Or, simply buy a new one from Ricambi.

 

Try Freeze Off. Shoot the nut and on both sides where the bolt goes in and out.
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What about straightening the clamp, grind the nut and enclosed bolt off with an angle grinder, smooth it and tack weld a new nut onto the clamp where old one ground off and use copper based anti-seize when re-assembling it? Use a grade 5 or higher bolt and nut. Should be good to go.

 

Clamp and bolt both almost certainly stainless. Typical of Ferrari. Stainless in stainless galls real bad. When assembled use some copper antisieze and you'll actually have a chance to get them apart next time.

 

Order a new one.
Always use copper antisieze on exhaust fasteners.

 

If it wasn't stainless steel I would have suggested drilling down the center of the stud to the depth of the underside of the nut which would have helped to relive some of the tension on the threads and possibly made it easier to turn. Trying to drill stainless steel is a bi**h!

 

I would weld the hex head back on the stud. That will heat the stud and break it up. Then unscrew as normal. It would take 5 mins!

 

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Technical documentation states single use clamp. Once they gall I just toss them and use a new one with some Molly grease.