If your cam has a lot of overlap, you'll want an individual throttle per cylinder, it'll lessen/eliminate intake reversion which will make it less choppy. Thats either going sidies or bike carbs, both of which will be minimum triple your budget.
A set of Coby extractors will help it breathe a little better if you're still running the stock exhaust manifold, though the stock 4-2-1 isn't actually that bad.