Which one is better in terms of speakers subwoofers and amplifiers. also can u recommenrd a good head unit for under 200. thanks alot

They are both better in their own ways. Infinity has fantastic sound quality, even when directly compared to Alpine. However, some of Alpine's products are very great at producing spl. To be honest, there aren't a lot of *good* head units for under $200. Most head units around that price will be very similar. Just look for one that provides the options that you like (satellite radio, mp3/wma playback, cd-r capability, etc).

personally i would go with infinty i had the kappa perfect 6x9s n they hit so the woofers hafta pound like mad

I have a '93 3000gt SL with Infinity in it and it rocks my world.