OBX Performance Exhaust Manifold Header 01-06 BMW M3 E46 S54 Engine Race 1-3/4x3". <br>Mirror Polish <br>4 O2 Bungs <br>Port- 1.7” ID <br>Primarily- 1.75” OD <br>Outlet- 2.3” ID <br>Piping- 3.5” OD OBX High performance racing headers are made out of pure SUS-304 stainless steel. Dyno tested at low end and top speed to increase horsepower. Precision mandrel-bend to enhance exhaust gas flow. These type headers are easy to install. Value-added bolt-on headers for any racing sport performance enthusiast. <br> <br> Mirror Polish Finish <br> Made of 304 Grade Stainless Steel <br> <br> Flange Thickness: 3/8" Runner Wall Thickness: 16 Gauge (1.5mm)<br> OBX High performance racing headers are made out of pure SUS-304 stainless steel. <br>Computer Numerical Control (CNC) machined flange for precision fitment <br>Dual Tungsten Inert Gas (T.I.G.) welding for stronger hold <br> <br> Increase Better/Smoother Exhaust Flow At Higher RPM To Generate More Power And Maximum Performance Out Of Your Engine. <br> Great Power Package to Unleash Hidden Ponies From Your Motor. <br> Get Up To 35% Better Exhaust Gas Flow By Replacing The Restrictive And Inefficient Factory Cast Log Manifolds With These Precision Built High Flow Headers. <br> <br>Value Added Direct Bolt On Set Up Without Any Modification<br> <br>Dyno Tested Track Proven Systems to increase Torque And Horse Power.<br> <br>Backed by OBX Limited Life Time Warranty. <br> <br> Don't settle for the cheaper headers on eBay which are known to crack over time due to cheap welding, thin flanges, and very thin wall thickness. Also comes with a lifetime warranty from manufacturer defects. Dyno proven to increase horsepower.