Look at the Pattern Forum. I started the thread on care and feeding of the SAP180 on pipe. Scan through it and pick the stuff you need. In the early pages I show what pipe and tuning length, header, coupling material that works, etc. Later pages we discuss how to keep the header on the xhaust flange. Both are critical pieces. It is a very long thread unfortunately....but there is a terrific amount of useful information from several of us that have gone down this path. We are the trail blazers on this type of application. We are developing the techniques as we go and are getting really great results

The tuned pipe will enable as much as double the pitch for a given diameter. It will also enable at least a 1"-2" diameter increase for a given typical pitch one would run with muffler. For example, I am running a 17x12 apc in a pattern set-up. Bob is running a 15.5x12 wide blade apc at around 9K rpm. I have run a 19x10 in a sport set-up but it's noisy (8.5 K rpm) for my taste (which doesn't mean much in a sport application, I know). The engine will turn a 20x8 on pipe at around 8K, but is noisy (high rpm and large diameter means noisy tips)