Searching the forum would be a good idea, but I'm bored so...
Port and polish - intake manifold and throttle body
Some people weren't impressed with the build quality on the Sikky headers, but I can't personally comment. Your other options are PPE and Elite? for headers.
Some people are also on the fence about intakes, the stock one performs very well. You could consider a drop in filter instead.
Nitrous kits have been the best way to make power so far. Supercharging and turbocharging generally fail because the ECU hasn't been cracked and there isn't an aftermarket standalone. Although it has been proven the stock ECU can work with low boost.
From everything I have read, I believe Elite has given up on the headers. After about a year, they have returned the Sikkys they were going to use for a comparison dyno. The Sikky's were never installed on a car.