250-500cc octane boost

who makes the best?

You mean octane booster in a can? They're pretty worthless. You're better off getting higher octane fuel. See if you get Avgas at your local airport. Your 2 stroke will like the lead. What do you ride and why do you think you need octane booster.

Everything you need to know (click on the pics for test results)

http://volvospeed.com/Review/misc_performance_volvo_reviews/octane_bosters_general.html

Some really do work.

interesting read, it supresses the ignition till the exact point of combustion. so no knocking pr pinking is caused.
whats the highest pump rating available over ther we get 97 ron here not sure of mon ratings tho, so may equal out.

Thanks Zomby, looks like Lucas gets the holeshot on the others,so one bottle mixed with 5 gallons of 91 may net upper nineties octane. worth a try.