Just got my Pacesetter header installed on my 86 720 and all I can say is WOW! A very signifigant increase in power.I ended up skipping the lower two pieces of pipe that come with the header and ran one piece all the way back to the converter (ran a piece of 2 1/4 pipe through the converter)and a Dynomax muffler.
I highly reccomend this mod!!

The headers gave you that much more power? Did you replace all the exhaust pipes at the same time?

Yep, very noticeable increase in power! And yes I put it all on at the same time.
Also took it on a 600 mile road trip this weekend. The addition of the header and exhaust as well as some lock-out hubs bumped the mpg up by 3!