Active ingredient in most of them is Toluene. If you can get your hands on that in quantity, you should save a bunch of $$$.
Most rely heavily on MMT, which is the ingredient that leaves the "orange dust" coating on plugs and O2 sensors. FWIW, even if the product claims to be safe for use w/ oxygen sensors, use of MMT with them has been proven to reduce their service life.
Brands that seem to offer at least some benefit, if using or blending "real" race fuel isn't an option, include Torco, Boostane and "Race Gas". Not saying others don't work, just that these have shown improvements in certain tests I've seen.
I've used some boosters in the past and may still need to in the future. However, IMO they're at best a Band-Aid to get by on sub-optimal fuel.
