This article is from the Car Audio FAQ, by Ian D. Bjorhovde (email@example.com) with numerous contributions by others.
Generally, companies that produce 1/3 octave (30 band) and 2/3 octave
(15 band) equalizers are good. These include AudioControl, USD, Rane,
Phoenix Gold. Most people try to stay away from equalizers that
contain a "booster;" these are made by Kraco, Urban Audio Works and