CAV's what brand of filter is the best ?

[Cuppa]

dont sell Ryco so I have very little to do with them. Even after a quick look I couldn't even find what micron it is on their website.

Yep that's what I found too.
Have since had a look at the Donaldson site & found they list the full specs for their filters, that sort of transparency has to be a good thing. They may or may not be any better than Ryco but at least you know what you are getting. I think I'll switch to Donaldson after I've used my current spare filters instead of the Rycos. Seeing the pics in their X902759 filter kit for my car it reminded me that I had had one of their air filters once before & liked the 'robustness' of the additional metal cage around the filter paper, especially when having to knock accumulated sand out of the filter on the bullbar .

Quite a variety of delivered online prices for that kit from $89 to $147.60 which pretty much mirrors online Ryco prices.

Looks like the Donaldson Delphi HDF 296 equivalent (P557111) is also 12micron @ 98%.