Jack Spania Racing K-Series Race Header RSX EP3 K20 4-2-1 2.5" CollectorJackspania Racing K Series Race Header RSX EP3 K20 4 2 1 2. 5" Collector Acura RSX Honda Civic EP3 & K SWAP EM2 Header is a race header designed with great power and pricing. The stainless 4 2 1 design makes for good low mid and high end power. Offering gains in the range of 10 15hp. The 4 2 1 optimizes scavenging with equal length stepped tube primaries ending at a 2. 5 Inch collector. This race header also includes gaskets & all necessary assembly