I have that pipe on my seducer sd1, and I love it!!! I have it on an older model OS RZM 21. it runs right along with a friend of mine in our club who has a MAC 21 with cooper pipe in a speed master hull. I run mine at 8 and 5/8 inches. don't cut the pipe. Swedge it. I used a tool that ac guys use. it expands the inside diameter of copper tubing. I used this on my pipe. now I slide my manifold into pipe and I can change pipe length when I need to, like when i change props. works great. great pipe for the money. works for me. they are loud. so if you don't like loud then don't use it. but loud is good. because when you are racing you can monitor how your engine is running. you are not out anything, because they don't cost much
Jim,