I currently have headers going into invidual pipes to glasspacks and exiting a bit before the end of my car. Now, I just learned that glasspacks are restrictive and plan to go with a less restrictive muffler, but what about X or H pipes compared to just individual non-connected pipes out of the headers?

I've been told that an X-pipe works like another set of headers... kind of like a y-pipe without the single pipe restriction. Plus, it frees up a lot of back pressure because the exhaust gasses can chose the path of least resistance which in turn doubles your muffler flow capacity so to speak.

H-pipes work the same way, but under higher rpms I've been told they are ineffective.

I'd go X-pipe, it can't hurt, and they sound really cool! graemlins/thumbsup.gif

I have an H pipe and dont really like the sound. It's too smooth if you understand what I'm saying. You cant hear the individual pulse of the cylinders firing.
Just not my preference.
Ron