Performance parts

Hi folks.
I'm just taking a survey to find out which perfomance parts to put on my D.
Its a 1999 SLT + with a 5.2.
I have a Magnaflow 3 inch cat back. K&N Air intake system.
I'm looking for something else to increase performance without going into the engine.
Any suggestions would be great.
Thanks.

Headers are a good idea.

Are you running headers?
What brand and are they strictly bolt on.....no sensors to worry about?
I was thinking either headers, ignition, or maybe a throttle body.

You could do quite a few things. Go to Krcperformance.com they're the best I've found for selection.
In addition to headers and throttle body you could add throttle body spacer, highflow cats with full exhaust (keep your cat back) High energy ignition such as Msd, hypertech power programmer, what K&N did you get the fipk or drop in? Fipk gives best gains, underdrive pulleys, electric fan conversion, ac eliminator. Hope you find what you need.