HPI Pigtail Pipe idle was around 90db and 95db at peak acceleration without the silencer.
With the Carbon Fibre DDM silencer the peak sound reading was 92db.
The DDM Silencer causes significant back pressure with the HPI Pipe which causes the engine to stall so I would not recommend the use of the silencer with the HPI Tuned pipe.
The Rovan Dominator idle is around 85db and between 92db and 95db under full acceleration unsilenced.
Due to the vibration of the silencer, the sound is around 90 to 92db both at idle and full acceleration using the DDM silencer.
I would expect the readings to fall back to 85db and 90db when the silencer is attached with a silicon hose.
There were no back pressure issues with the dominator and the DDM silencer.
Thanks to Baja Brad for the Silencer and Large Scale Down Under (http://www.largescaledownunder.com.au) for the assistance.
Conclusion is that the DDM silencer changes the pitch of the exhaust note and doesn't materially impact on the volume of sound produced. For those RC that find the mechanical 'thrash' of the standard HPI SS Pigtail pipe annoying, the silencer will help address this but you will need to change the pipe to make it effective.
