Looking for an easy way to watch the performance numbers of your BMW E46 325I 330I climb? It really is a simple solution! Swap the E46’s factory header with integrated cats, known to be highly restrictive, for a BMW E46 performance header that is much more free-flowing.
There are a few problems when it comes to the factory manifolds of the E46 325I 330I, which are the reason owners aren’t releasing the full potential of their BMW. For one, the exhaust catalysts are situated right against the cylinder head – which cause an extreme amount of heat to build up. Also, cylinders one through three, and four through six, are each channeled through a single pipe, greatly restricting the air flow. These characteristics are responsible for the production of more heat, due to an inherently bottleneck system, which effects the overall performance and power of the car.
To address the problems with the factory manifolds without compromising durability, the stock exhaust catalysts are removed when the Active Autowerke 3-series sports header is installed. These E46 performance headers are constructed completely from 100% polished 304 stainless steel and the gains produced have been dyno-tested. Be sure to check out the Active Autowerke E46 BMW rear exhaust for even more horsepower!
FYI here is an image of the restrictive E46 325/330 stock header...