Ron.... I used to use a header that was a copy of the NISMO but was a step header. It had slightly smaller primaries. That gave it a lot more torque but cost about 2 peak HP. I got it from Sam Moore. It worked well but I later switched to the Sam Neave header. I haven't been able to do side by side dyno evaluations but it appears that HP is much higher. And the sound is SWEET!