RE: whats the different between tune muffler and tune pipe?
Pé,
Maybe you did not, but please read Chris' post and your reply once again, to understand why I reacted with my statement.
It was not completely clear what you were responding to.
I agree that boost should be measured, comparing the power to the open exhaust condition.
But since hardly anyone runs a .15 or larger engine with an open exhaust, comparing power with a tuned system to that of a normal non-tuned system, is quite legitimate.