All,
Here's a site you can use to design your own tuned pipe. It's in German, but the pipe design part is in English:
http://www.kreidler-verein.de/reso.html
I used this to design a pipe, it ended up being slightly larger than my design, but overall pretty similar.
FYI: On the Spree, the exhaust port angle is 140 deg, transfer port 104 deg, exhaust port area is 225 mm^2. Use exhaust temp of 600K. The Spree tops out around 8000 RPM at just under 30 MPH, so you can either use that as the RPM or go higher/lower.
Have fun, post questions.
Design your own tuned pipe
Moderator: Moderator
drichardson@core.com will sell just the downpipe with no muffler for a good price. I'll bet if he's got 50 sprees out there, more than a few have rusted mufflers.