For my evo, the manual says adjust to 1000-1050 RPM's, and as mentioned, the oiling system on an evo does not have the pressure at idle speed like a twinkie does. YD

 

totally right on , hard on the engine. multi-valve head will never sound like that.
next best option, fake it like they do in some cars. the link below is an aftermarket version
find a old rat and record your own and throw into a nice bike stereo, shoot, GOAT exhaust and intake will throw any hd riders off, be prepared to explain all the exotic engine upgrade you put in.

http://www.soundracer.se/?p=98