^^^^^ the only way the dc header would increase hp is if you have a APEXI Power FC(computer managment system) that lets you tunne it to get the most out of it, or if you have high compretion pistons, other than that i would just port your stock header like i did check it out https://celicahobby.com/ubbthreads/thread.f_1953552130_0_collapsed_5__1.html
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