A replacement filter is just as it says, it is the same size as the OEM filter, but is washable...
This is an induction kit...
Much nicer noise, but next to no extra power...
Note: You don't get the Stainless pipe with it, you get a silicone one...
Don't run your car without an air filter, just think of all the crap that will get into your engine (Not nice, think of it as riding a pushbike with your mouth open )
Yup, you'd want an enclosed one. Either the piperx viper or the BMC. Personally I'd go for the viper as I've seen a BMC and was not at all impressed by the quality.