I don't really like that PRL intake. It's super ugly. I think if you just want a 3.5" tube, there are better looking options out there. Honestly, if there were a way to couple the stock airbox to a 3.5" tube to the ZDX throttle body, a K&N drop in filter would probably be the best thing. People really like relocating their battery and putting something that looks like the piping for a pool filtration system in their engine bay, though, for some reason.
All that being said, if and/or when other people get the RBC/ZDX set up on their cars and there is a proven, substantial gain in power across the band with an ugly 3.5" tube, I will shut up and buy one. I can't see that happening, though. My next step is to get a 4"-3.5" coupler, run it to a 3.5" elbow and run that to the ZDX. My buddy is an awesome welder, so hopefully I can get it done soon and have it ready to compare with the 3.5" CAIs that are bound to be on the market very soon.