Exhaust size velocity vs volume

[Vortex-98]

I'm trying to get the exhaust sounding a bit better ,I'm getting sum new headers but when it comes to size it gets a balancing act ,the smaller diameter exhaust pipes better for velocity an moving the air faster than a bigger diameter which is more for volume r but as it has 2 pipes on the inlet the noise they make isnt pulsing in harmony an they cancel the flow of the other making for a stock idle..