I have a P-Flow on my Golf but I didnt feel any difference from the P-Flow from when I just had the airbox cut. I took my air box and cut a huge hole in the bottom. It had the cool sound and give me a little difference. But just modify the box. If you need help then give me a call bro. Ill help your cut it apart.
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2003 Volkswagen GTI 1.8T Silverstone Grey