Horse power drop using early A 273 manifolds

66fs said
They were loud since the muffler was 2 1/2 inlet with a 2 1/4 core straight through. Not sure when they put the baffled muffler on the Commando. I know the baffled muffler was on the 67 for sure as I have that system NOS as well. I have an Accurate system on the 66 Formula S. I got the straight thru muffler since that was what I had on my 64. Not sure if the straight through muffler is still available from Accurate. The Accurate system is not the same as the OEM system, but fits well and is very similar in sound and power to the 65 Commando exhaust.

Yes it must have been a rumor I read about there being no muffler in 65. I edited my post above. The original mufflers were straight through and there was a service bulletin about the issue. Here's a good thread from a few years back with some good photos and information. The real 273 HP exhaust sound