2X76mm / 2x3". Originally developed to BMW Motorsport chassis track E36 M3 with Supercharged S54. Single 4" could not fit past the supercharger so instead two 76mm / 3" hoses were routed different routes to air filter.
See options list to select also exhaust side counterpart that best fits your needs.
You will need to purchase separately and add exactly M3x5.7 size Threaded Inserts and exactly M3x8 size bolts. Preferably DIN 912 A4 Hex Socket Screws.
