The Cessna 120-140 Association Forum

Hi All,

When changing from the pancake mufflers to a 150 exhaust system, how in depth are the modifications required?
Do the cowl holes match up?
Are there any other changes that need to be done?

Thank you

Although I have not done the mod I do have the STC. You do have to cut new holes for the stacks to go thru the lower cowl, so would also need patching the old ones....
Also mentions modifying the cabin heater duct