I fly a os. .61 Hanno and the associated pipe APC 12x12 at 9800 rpms and my aircraft makes less than 93db. Noise is an issue at alot of fields and there are pipes that will meet requirements at any field Macs sells them hatori also and to my knowledge they are quiter than the 4c that are running standard mufflers. Running a baffled tunned pipe only cost a couple hundred rpms. So the SPA argument that 4c is not as loud as 2c on a pipe is BULLLONEY!!!! My plane is not as loud as many of the .91 4c that are flying in the SPA.


I would love to pylon race a SPA legal aircraft to prove that the speed of the two styles are relatively the same...


gary