it is a SCAM....wasted $75 few years ago....couldn't agree more with ZZman......what they claim is that their product accelerates the speed at which the air enters into the air intake valve...which is not true...it actually blocks the passage hence allows less air flow
once known as twister....anyways lastly....it causes problem...it directs the air to center of the air filter (if u have a flat square/or rectangular shape filter)...so now instead of the whole air filters surface area filtering the air, only the center part gets to mainly filter...rest of the area doesn't get to filter much....
i figured this because every time i took my K&N air filter out to inspect...all the debris, dust, insects, mini stones were stuck in the centre...rest of surrounding area use to be clean....so MAD...flase claimers like these should be FINED!