It's looking like I have a cracked exhaust manifold (already had the gasket replaced) and considering how inexpensive the Speed Daddy headers are, I figured I'd just go with those instead of OE-replacement stuff. Which got me thinking...

Without having to reprogram anything, what are some other mods I could do on a reasonable budget?

As I understand it, the headers alone will net a performance increase? But do they necessitate that I make a cold air intake setup?