Application: 2006-2011 Honda Civic Si
Design: 4-2-1
Piping Diameter: 44mm-54mm-70mm

The Invidia header for the Honda Civic Si is made from stainless steel which is polished, this header not only performs but it is a piece of art.  The header is a 4-2-1 design which is stepped in size starting at 44mm, enlarging to 54mm and then ending at 70mm before exiting to your cat-back exhaust.  Invidia has dyno tested the header to produce power gains of 20whp and 11ft/lb of torque.  There is a flex section after the 2-1 section to prevent cracking, top notch stuff from Invidia.