dump pipe- twin dumps or single

[Mase]

I'm still deciding on my exhaust and want to make sure it is one that makes a fair difference. I've been seeing a few cars making decent power with twin dump pipes off the turbo instead of one single 3" pipe. Does anybody have a setup which they have dyno testing to prove a recommendable amount of increase in power to their rb20det. Could you please list your setup for me? I don't wnat to make a big mistake and buy an exhaust only to not fully utilise the power of my car.

Thanks