ORIGINAL: seanychen
About the OMP MCP, maybe they mean 1000 rpm gain from stock muffler, which may be weaker than BCM Pitts. That stock muffler is next to useless: heavy (10 oz, 1/3 of engine weight, structurally unsound, and now power robbing? The only virtue of that muffler is perhaps providing back pressure and muffles.)
I will answer my own questions here as now I have the answers and others in the market I am sure would like to know.
Header length is 10" - Macs standard header. Total length from beginning of header to end of stinger is about 32"
No it will not fit in pipe channel. It is about 4" to long, but is not to bad hanging out.
The + 1000 RPM is with 18 x6apc prop--This sounded like a lot to me and on my recent bench test the pipe yielded this for me:
I had a chance to get out and get some test stand #'s on the OMP pipe today. OS160FX , VP30 Perry Pump & CP10%/Omega 5% 70/30 blend fuel. Thank you aerobob for a properly broke in 160FX—it is turning the XXXX out of the 18x6W!
With Bison pits & APC 18 x6w 8940 peak wav file -- bad sound quality
http://home.comcast.net/~ccrsfield/18_6W_bis2.wav Spool was fine for 3D
With Bison pitts & SKorepa 8800 not peak - very fast spool
http://home.comcast.net/~ccrsfield/18_6SK_bis.wav
With OMP pipe & APC 18 x6w 9080 peak fast spool, very loud down low!
http://home.comcast.net/~ccrsfield/18_6W_pipe2.wav
Open face & -----APC 18 x6w 9200 peak Good spool
http://home.comcast.net/~ccrsfield/18_6W_open.wav Motor ran good with no backpressure
The pipe was very loud at low rpm. At low rpm it had a rap sound that does not come across in the sound file very well. I think that in IMAC it would earn a big fat 0 on sound and they would ask me to change my pipe. Also, I don’t think my club would be happy with me running this pipe. If they did a sound check there is no way it would pass at idle. It did not seem to get any louder with increased RPM.
Performance increase over Bison muffler with 18X6W prop was a dismal 140 RPM. There was no tuned effect as the open face reading was almost 100 rpm more. Spool did improve from the Bisson muffler with the 18x6W, so I think the pipe is long and would benefit from a shortened header or heaver load prop.
http://www.rcuniverse.com/forum/m_30...tm.htm#3541924 post#807