Firstly, welcome to LOC. :)
If you need to be careful of noise, the don't go for the induction! It's loud! Think about an exhaust (5hp ish) and maybe a manifold. Change your sparkplugs to cooler ones while you are at it.
I would suggest you look at anti-roll bars as they will have a big improvement on reducing the roll on the IS. Coilovers are always a worthwhile addition if you can afford them.
Hope that helps a little... :)