I have a new supercharged 540 being built for my hallett and need some new mufflers. I currently own some IMCO mufflers however they are not rated for the 750hp that I'm expecting. I was thinking on getting the Gibson bulletts with external flappers or the CMI mufflers. My IMCO mufflers set in the water 1 to 1 1/2" inches at idle and I need some protection from possible water indigestion.

Does anyone know which muffler is quieter at cruising speed (45 - 55)? I can get the CMI for about $950 and the Gibson are a lot less at $570. I just wanted to get the quieter muffler for my wife even though both are gong to be too loud for her.

Any suggestions????

ttt

How 'bout IMCO Gatlins....

Gibsons...hand down. The CMI open mechaically at speed.
Almost as loud as open exhaust.

I need protection from water ingestion due to standard risers and the exhaust mufflers will be touching the water at idle. I can either run Bullets with rubber flaps flaps or CMI's.

I called some vendors and they all say CMI is a little quiter but no one has hard data.

Have you looked at GGB. I run them on 600 CU IN NA engines. They are full time and really cut the noise down with no loss of power.

GGB mufflers do not have precautions for water intake, no flaps or mechanical device to prevent damage to the motor.

Or am I wrong?