Jazz cat stud/ bolt size

[90Ninety]

So I have a replacement Mid pipe

The old nuts from the Cat side of the mid pipe ( towards the font ) are buggered and I need to find replacements ( preferably brass)  , but the old studs ( seem to now be welded , perhaps were once bolts  )   I am trying to understand the stud/bolt diameter .. The pitch is 1.25 ( checked with a feeler gauge ) , the vernier gauge states around 9.4mm something ..

This video @ 1:26 shows the three mysterious studs   

I tried running a 10 x 1.25 die  over the stud but , its way too tight , the die got pretty chewed , not sure if die is ********** or if  I am just confused

[CRC]

I don't know for sure, but if the studs on the Honda cats are similar to the Porsche Boxster cat studs, they will be a nightmare to tap or remove.

On the Boxster, the studs are made from a very hard tool steel that is splined into the cat flange (during manufacture) from the cat side of the flange. The threaded part then corrodes away with the nut and will often rust solid in the flange holes. They are impossible to drill as they are harder than the drill bit.

On mine, only using an oxy acetylene torch to heat the stud to cherry red then quenching broke the corrosion enough to free the cat.

Some scumbags pinched our genuine cat, but the £65 replacement has been as good as gold for 6 years or so, and if all else fails, the scrap value of the genuine cat will almost certainly pay for the replacement.

[embee]

Just a thought....
Standard metric "coarse " threads are M8x1.25 and M10x1.5
Many exhaust studs in my experience are metric fine, M10x1.25
Are you sure you are not trying to run an M8x1.25 die down the stud?
If it measures around 9.4mm it will almost certainly be an M10 with a truncated thread form, or if you are measuring a plain section that would allow for the increase with thread rolling manufacturing methods.
Just a thought  .......