As far as I know the Cupra R has no chance to install a CAI system, due the double intercooler, there is no space. Eventhough I know some mates here in Mexico that has adapted the CAI to their Cupra R.
I have a Leon 1.8T (non Cupra R) and have a Carbonio CAI installed, and let me tell you that after the chip, this has been the most satisfiying mod: the grrrr sound on idle and low rpms are great, and the grrrr - pssst sound on the cruising and gear shifting it´s amazing.
.
I have more than 3 years with the carbonio and has no
problem at all. The
problem with the high flow filters on a 1.8T came when you installed them without a CAI pipe, I mean when the filter is just put with heat deflector on the engine bay, that affects the MAF because the filter oil and because the engine heat, you can even burn down your MAF with the hot air coming in from the cone air filter.
For your Cupra R, check out this filter:
http://www.ttstuff.com/performance_airintake.php
I´ve seen that filter induction system installed on a Cupra R, not the "grrr" sound but performs nicely!!