Love the sound of the BORLA but its lack of a valve system is what puts me off, a child with ASD and sensory issues aswell as some lovely but elderly neighbours and a wife who works nights dictate I need a "stealh mode" when I manage to get my V8 F of Lexus variety .
I am quite fond of the GTHAUS system, with closed valves it's rather subtle, then open them up for a pure roar of sound.