Tough crowd - All I was doing was trying to make two points - #1 - that Flowmaster mufflers are also available in stainless steel with a 10-year warranty. #2 - that flow rates on mufflers and muffler products are not a true indication of power and torque generated by engines, dyno numbers are the only way to measure that result.

 

Not so much as a tough crowd as it is a crowd who has owned one at one time or another.
It may be true that the stainless muffler is better, but I don't think that's real comfort to tell someone who has their Flowmaster rust out in no time "you should have bought our more expensive stainless one". The truth is, the standard FMs rust faster than most other non-stainless mufflers.

Also, I would agree with you that the only true test is on a dyno. But common sense would also tell you that if the muffler has a poor flow rate, it's not going to be a solid dyno performer either.

I do have dyno numbers of a 2002 Mustang 5.0 with stock exhaust, a Borla, a Magnaflow and a Flowmaster 40.

Stock 365.2 HP 330.1 TQ
Flowmaster 369.4 HP 331.8 TQ
Magnaflow 372.8 HP 332.5 TQ
Borla XS 373.3 HP 332.6 TQ

 

The flowmaster had a (69) in the hp reading..........nothing? lol.