My 318 dyno results
Many years ago, I was pulled over for a noisy exhaust, but the copper gave me an out (1975, when cops were still good guys). He said to fix it and report to the office on a certain date. I did that and passed.
What I had done was roll up some corrugated cardboard, about 20" long (going by memory) and stuffed it far enough up the pipes that he couldn't see it, without getting down on all fours with a flashlite. I was betting he wasn't gonna do that, and I was right. I kept the cardboards in there with nails, dropped in from the top which also could not be seen.
Of course as soon as I was out of sight of that copper, I pulled the nails, rapped the pedal and shot the cardboards out the back like a brace of canon.
That cardboard trick works pretty good.