[metalhedskater]

1. HIDs anywhere from 300-500
2.Yep you can get some high flow cats from summitracing.com i would say or any other performance store. Cost: 100-300
3. YEa i think most exhausts are smog legal. Im pretty sure most mufflers are smog as well. Anyway, i wouldnt really worry about it unless your local law enforcers are very strick on it.
4. Yes you can but you may need to get a special flange to fit on your stock ICP. I would go with a cheaper option which is the 1g bov for a bout 50-80 new and 20 and under used.
5. Umm not sure, but i would just leave it.

Also, next time leave the year and type of dsm you have i.e. turbo, n/a. Hope this helps!