VorTTC

I have used a well-known aftermarket air filter on normally-aspirated engines with positive results. (Not astounding results, but probably worth the money). But isn't it reasonable to say that with an electronically-regulated turbo that aftermarket air filters would generally give marginal increases in performance?
(donning flame suit...)

Quattrings

I added their setup to my car, and it seems to work as advertised. The car is noticably quicker, especially when the weather is "cool". It seems that the p-flow takes away from the "consistent" performance of the stock airbox though. Performance seems to be relative to the temperature outside more so than compared to the factory airbox. Air rushing through filter is much "louder" and can be heard whenever the turbo spools up, can also hear the factory bypass valve when shifting.