Does this look like the same or almost the same performance....NOT..
Results
Each manufacturer will perform diff like a Volkswagen vs a Porch..I'm sure you would see similar diff. from the 18/6... None of the 18/6's will perform well on that engine..under propped...
Results in 18/8
Zinger Pro 8900-9100 104 Rpm Decibels at 10 feet
Apc 8800-8900 Rpm 102 Decibels at 10 feet
Mejzlik 8400-8500 Rpm 96 Decibels at 10 feet
Menz 8100-8200 Rpm 96 Decibels at 10 feet
Perry vp-30
Bisson Pitts Muffler
15% Fuel
in San Diego, CA
this is from 2 different planes and both 160 OS