About civic parts what brands are good and what to look for?

Without checking to see which companies have suspension parts out for the new 03 si's, I direct you towards some pretty reputable companys. Koni Yellows are some of the best struts around. If you want coilover sleeves Ground Control is a good brand. For true coilovers go Tein. It all depends on how much you want to spend.

For wheels, it depends of the amount of money you want to spend. For light cheap cast wheels I like Rota's. For light expensive forged wheels I'd go with Volk, SSR, Spoon....