Additional exhaust side rocker breather?
 

I’m looking for something like in attached phot as an additional exhaust rocker cover breather?
Does any one have one for sale/ know who might sell them?

Forgive me for asking... but why do you suppose it is necessary? I would have thought the existing breather would be sufficient unless you have excessive blow by.?

New built performance engine so want to see if it has any positive impact.

Personally, I think I would fit a PCV valve.

If so send a link to a suitable one please

PCV valves are readily and cheaply available on line. They come in many different forms but I think they all work in a similar way. I don't know which one would work best in your engine but I would suggest keeping it as simple as possible. You could perhaps fabricate a grommet fitting in the valve cover or perhaps adapt the filler cap. You would also need a hose taken to a suitable point on the inlet manifold from which to obtain a vacuum. No doubt there would need be a bit of experimentation.

An alternative solution would be an exhaust extractor system with catch can. I have used this method on my supercharged MG TC XPAG engine to replace the draft tube. It is a popular option with forced induction systems where PCV valves do not work as well as in normally aspirated engines.

Thanks for that information.
I’ve been reading further about breathing via an excellent article I found, and will start by actually measuring the actual crank case pressure using a pressure sensor and scope before I look at additional breathing systems.
Credit to author
Digsy” for Vortex-Power.co.uk and MKIVSupra.net 22nd August 2005[php][php]

I would suggest you speak to IN Racing. They will know what your best options are.