Which setup would give me the best sound?

I've ordered the BW diffuser exit resonated race exhaust but it has not shipped yet so I can make adjustments so that got me thinking. I already own a CPI RTX so would the diffuser exit street version (attaches to section 1) sound better w/CPIRTX or the full BW race res exhaust? I've seen one member of M3forum.net did that but the video didn't work. I've heard both of them have almost no rasp but I'm not sure if I want the H pipe section one again. What would you guys go with? Keep the full BW race res or street version w/ cpi rtx. both diffuser exit, of course.