If you want to stay with your stock airbox I suggest our Green air filter.
Our Active Performance Green filters Are excellent and have a proven track record over on m3post!
Why Go Green?
The Active Autowrke N55 performane filters is designed from inception to have that BMW factory like appeal added with the Active Autowerek philosphy to deliver true perfomance. The end result is a direct drop-in style fitment that lets your engine breathe more effortless while delivering dyno proven horsepower gains.
Time tested on matching the right pleat design with the optimum filtration were all conducted on the in-house Mustang Dyno, here at Active Autowerke. The end result is a product that performs on par or often excels when matchd against the competition.
Simple but functional, this performance product does the job wonderfully.
This is a direct drop-in filter that fits into your factory air box.
Application fitment for 2011+ BMW E9x 335i (not335IS), and 2011 + BMW E8x 135i.
The Active Autowerke Green Performance Air Filters are uniquely designed to take full advantage of cottons capabilities.
Unlike multi-layer gauze filters which can fray and release fiber particles into your engine, our filters uses two layers of tightly-interwoven cotton fabric. The 3 main benefits to woven cotten are the fact its thinner, holds oil better, and is stronger. Since its thinner, it allows better air flow without sacrificing filtration. The cotton holds the oil more evenly, and the medium is much stronger. Unlike gauze, you cannot wear a hole in woven cotton by rubbing it, and there is no way small bits of cotton can rip off since its interlocked with another piece.
Cross weaving one fine, and one medium layer, produces a fabric that is thinner and stronger than other materials and has the ablity to trap dirt up down to 5 microns. The result is better airflow without sacrificing filtration. And because the fabric is so durable, they can be washed and reused over and over, which allows us to give it a lifetime gaurantee.
Hand molded flexible rubber base on filters.
Green Filter USA rubber molds create air tight seals. We also feature trim-able custom fitment tabs on all filters.
Green Filter USA uses deeper air filter pleats which creates 20% more filtration surface.
Race proven gains and technology.