I have said combination in my 2007tt. With the factory setup, the y pipe has 2 nipples that sit in holes in the stock airbox to keep the y-pipe from popping out of the square rubber connector. With my werks composites carbon air box, there is no place for the y-pipe nipples to drop into. It seems a little flimsy but I've only had the y-pipe come loose from the square rubber connector one time. My question in all this as I get ready to drop my car for its 20k service: has someone done or seen something to make this set up more robust? Should I ditch the carbon fiber airbox and go back to stock? I'd prefer not to as it looks pretty cool and I just ordered the replacement air filters for it.