Velocity stacks are the lace teddies of high-performance engines. So when Chicagoland's Fluid Motorunion wanted aluminum horns for their project BMW M3, they ran to the AutoCad and created a mockup. Then, they carved out these nasty sombitches in three dimensions.
The shop did all the conceptualizing, designing, cutting and assembling in-house — using 6061-grade aluminum, a part-magnesium alloy used in both automotive and aircraft construction. An Aquamist water-methanol injection system runs from a tank at the rear to a manifold that leads to eight direct-injection nozzles. These nozzles sit at the tips of eight arms that reach over the stacks (those are those gothic, flying-buttressy things). The designers wanted it to look mean. Mission accomplished.
Now that summer's here, we're pretty sure this M3 will be naked more often than Kate Winslet. (Thanks to MM for the tip!)