Exhaust manifold - butterfly valve?

[Jordan]

I see my S2A has the remains of a valve in the manifold, part of the hot spot system. The external weight and spring etc are missing, and the valve can move freely.
I notice the S3 wreck I bought doesn't have this butterfly valve, so I guess it's not needed and they deleted it.
Is it OK to leave the valve loose to move, or should I restrain the shaft?
Should I be worried that exhaust gas can leak out of the spindle hole?

I was thinking to install the S3 manifold, but alas there's damage on the pipe flange.

Jordan

[Blknight.aus]

lock it open.

it helps in a few ways, none of them really important in australia as we never really learnt what cold means compared to the UK and Europe.