This thread is designed to highlight a few products and answer any questions you may have about the different Header and Uppipe options there are for the WRX and STi.
After thousands of dyno pulls with hundreds of different header and uppipe combinations we have found what works well and what doesn't.
First off, from our findings, the hands down best header (and uppipe combination) on the market today is the GTSPEC or Tomei UNEQUAL length header & 3bolt uppipe combination. We have tested this header combination against the Cusco, Perrin, GPmoto, and many others and have never seen anything come close to the power in terms of spool-up, top end power, and mid range torque. The UNEQUAL length header combo also keeps the nice boxer rumble we have grown to love from an opened up EJ turbo motor.
The primary difference between the Tomei and the GTSPEC kits is the Tomei kit comes with header wrap and steel ties for the wrap. Both feature the same 4 to 1 design, machined cast flanges, full stainless steel construction, and 3bolt 2.3" uppipe w/ venturi technology.
Tomei Header & Uppipe Combination
GTSPEC Header & Uppipe Combination
More to come!