UEL headers are nice, not sure about the hp gain, but to keep the heat under control, they need to wrapped with exhaust wrap. To me, this means the pipes must be stainless steel. It's a lot of work for a bit of boxer rumble. :wink:
My goal is to get a little more power out of the NA. I know how I did it in my Focus, and I turned it into a fun little car. Didn't mess with the suspension other that strut tower braces. The car handled pretty well as it was.