what can i do to my 2004 harley sportster to add some power?

i have a 2004 harley sportster, i have the screamin eagle exhaust and air filter but what else can i do to it and how much would it cost?

Harley Davidson motorcycles. What actually defines a bike as one?

Is it the gas tank? The air filter cover? The frame? There are so many motorcycles that look like a Harley. Some even better and cheaper. For example, Independence makes a beautiful bike that uses mostly the same parts. Custom bike builders use the same parts. But what part makes the bike a Harley?

06′Harley performance parts?

I have a 06' Harley Davidson Night Train with the 88 cubic inch and 5-speed trany, with only 2,834 miles on it. so far I installed a Thunder Header exhaust and a power commander and a after market air filter .I want to install some high performance parts in the engine (internal parts) what is the best cam to install in a 88 cubic inch Harley motor?