OK you pressured me into it. I just purchased the expansion chamber from Dave's. It should be here next week and I will have a full report posted after install and testing. They also had a nice deal on a carb which I bought too but I will save that test for a later day.
I have two of them sitting here very lonely waiting to make someone very happy. Click on my signature link and go to the page about the Jaguar pipe and you'll see how to purchase it.