I know that using octane boost may not be to everyones liking but are there any prefrences of choice if you had to use it if you couldn't get super unleaded for your chip?

Millers octane booster is very good

http://www.camskill.co.uk/products.php?plid=m1b42s26p1390

not badly priced either.

Doc Frag is the best to ask he has tried a few

I'd definitely use Octane booster for track days or 1/4m days. Not only will it give you extra power, but also extra safety. Not good to use all the time though.

http://www.camskill.co.uk/products.php?plid=m1b42s26p2404

Thats the stuff you really want. Millers CVL Turbo.

Just seen the price there. If enough peeps are interested I could contact millers direct as their distribution place is about 10 miles from me?

I used 10% Bio-Ethanol on my last track day in conjunction with V-Power... should be around 100-101ron with that mix

Not good for use all the time??

Is that still the same if you don't have a cat?

Not sure all the inns and outs, but could in theory damage the fuel lines and also burn out the valves.