Look into Spectre as well. It's the same thing as Roto-Fab but half the price.
Picks up the air from the same place, that is all that is similar. Roto has a molded housing with air pick up at the bottom.
OP: search a bit, here and other board. Wealth of info as well as images.
FWIW, you may consider a yella terra tube also to get rid of the Helmholtz chambers on the stock intake. The stock filter/filter house can't be that bad when many of the blower folks use them...without concerns. Most numbers quoted are gains that also include tuning. How much is CAI specific and how much is tuning is tough to separate (IMO).
That all typed, I have had roto-fab and now VCM OTR. Since I don't track mine or have dyno, I really can't factually state a performance difference in numbers. Both are highest quality, no homebrew/ricer appearance at all. I ended up with VCM used on a killer deal. I believe the otr will have better flow and it looks factory which the rotofab does not, but close.
It's really personal preference,