I had read in the past of an exhaust used on a go kart that had a similar sliding body. So I thought I would to see how this had been done, but searching through the Internet couldn't find any reference to it.... but I did find this link, its to a scale model engine exhaust, that uses a spring and escaping exhaust gasses to shrink the exhaust at revs... http://www.bukupower.com/ Very Cleaver I think...
Look on the left of the screen,"How it Works"... when you click the link
If you click on "View Animations" from the first link then this gives a good explaination of tuned lengths ... Correct , Too short, & Too long..
