Why 2 Different types of Engine Pipes on Ecotec V6 engines ?

[Not_An_Abba_Fan]

When fitting extractors, this flex is removed anyway, but the extractors add a different element to the exhaust and changes the harmonics as well.

Yes, you can fit the non flex engine pipe, but you may get some extra vibration or noise that wasn't there before.

 

[_R_J_K_]

That reason is far more interesting that I originally imagined.