And aluminum sinks energy too well. Keep the heat in, push it out the pipe not through it.
I have a pretty thick walled aluminum exhaust. Think about what you just typed niggle... After the pulses make there way through the turbine... restriction is the only concern, not the endo/exothermic properties of the fucking exhaust pipe material ;O)
And I do agree Aluminum exhausts tend to be louder... Then again mine is 4" and stops right below the rear seat... HAHAHHA
My car sounds better than Alex or Mitches did with 4" Aluminum exhausts with the mufflers at the end of the system, then again the material they used was WAYYYYYYY fucking thinner too. Both of theirs ran all the way out the rear too...
I have a 4" Magnaflow "race core" muffler right under my shifter...