Yeah, I'm being anal, but given the affect an exhaust can have on performance is down to acoustics and pressure waves within the piping, I am assuming that the tailpipe design itself will have some impact on the performance 'gained' so to speak.
I was bored enough to wonder how the acoustics of a twin-pipe design such as mine differ from a single pipe? The pipework on my Cybox splits into two via a Y pipe within the rear silencer, whereas a single tailpipe design would go straight through the rear silencer and out the other side. I'm guessing the Y design would have a fair impact on flow, but I really can't find anything to let me know if I'm being really stupid and boring to be thinking about this, or whether there is any truth in my inane thoughts and ramblings?!?