X-pipe +1
Your stock ignition is good for a lonnnnng way from where you probably are, right now. Just keep some good copper plugs and quality wires/cap/rotor on there, and you'll be fine.
The X-pipe will not only give you a tad bit more oomph that you can feel, but it'll sound a LOT better than the OEM crap, or any cat'ed H- or X- for that matter.
I'd highly recommend the Jeg's Off-Road X-pipe. It's a three-piece design that's plenty easy to bolt n' clamp into place, and it has OEM-style tranny crossmember hangers, so it won't droop or sag on you like a lot of other X-pipes that don't have them will tend to do (such as the UPR or
Pypes X-pipes). It's also plenty cheap - mine was about $175, shipped. If you want something pretty much rustproof in stainless steel, though, you're gonna have to cough up a lot more change -
Magnaflow is a pretty good way to go with those, from what I've seen.