1) An import runs a little doggy on Optimax only.
2) A bottle of Millers (almost 2 RON per bottle) makes a noticeable difference.

3) A bottle of NF One Shot (Orange bottle, 3 RON per bottle)is as noticeable again as Optimax + Millers - really surprised.

NF One shot cost me £3.70 a bottle from Len (Subaru4you - Reading), whereas Millers after VAT and carriage came to £3.50 a bottle. I've also got a bottle of NF Race which I'll be trying at 75ml per tank

 

I had gains of over 20 BHP at the wheels from ignition timing I could add by using NF, albeit in rather large quantities, but 2ml/L should be quite a sweet compromise between detonation control and price. There are diminishing returns as you increase the dose much beyond 2ml/L.