Find someone with an SRT that is upgrading to long tubes and buy their SRT headers.
Bolt right on and don't hang too low if you ever decide to have the car lowered.
The exhaust headers don't go on easily, even with a lift. You should be able to do a "search" or ask a site vendor who sells headers. (also, you'll need the SRT mid-pipes or aftermarket mid-pipes) Personally, I like dealing with Josh at High Horse Performance
Changing a camshaft isn't the easiest task either, but the sound of the lope is nearly priceless.
As far as headers, generally if you want higher end HP go with shortys, or long tubes for low/mid range torque. Then there's the option of catted or catless midpipes, catless means more power but you won't pass emissions. I personally went with long tubes and catless mids, just your preference.
Tuning, necessary for basically any performance mod you do. Most folks use a diablosport predator or trinity. It's a handheld programmer you plug in to the car and modify stuff.
Cam is short for camshaft, cams give some serious gains but take real tuning by someone who knows what they're doing.
functional hood scoops
BT catch can
K&N air filter
That and some JBA shorty headers will put you up to about $2000.
But, you might want to consider suspension mods. The Eibach Pro-System kit (springs and shocks) can be had for around $600 (not including install). A custom tune after bolt on mods would also be helpful.