[puddleglum]

I hear you. ABA testing on a belly pan is not an easy task. Even on a simple pan like the one you built, it is quite an undertaking to take it off and reinstall it. Still, it would be nice if you could post avg. mileage data from before and after. I assume that you track your mileage. Once you've had a chance to run with the pan on for a while, you should be able to have a pretty good idea of % of improvement. It's not as good as ABA but it's more accurate than just saying that you had good mileage on one tank.
I am amazed that the exhaust hasn't melted the plastic. I had to leave quite a large gap around my exhaust and shield the pan with fiberglass to keep it from melting.