Are equalizer car amps good or bad?

[danger:wildman]

I have a regular cab dodge dakota truck and I'm looking to improve my stereo. Last summer replaced both door speaker because one was blown out(bought my truck used) and I removed the old headunit and installed an alpine unit. I've been reading review on a couple of different brands of equalizer amps on amazon. I've been told an equalizer amp will improve the sound quality. So can anyone give some advice and if equalizer amps are any good