mxt_77

Do you have the graph? I'd like to see the comparison of the two curves. Most of my power loss was above 7000 RPM where, I assume, the ECU was pulling timing and adding fuel (I know it was adding fuel, 'cuz I can see it in the A/F map).
You might also try doing the MAP sensor whack just to see if that makes a difference. I did that and it felt like it helped, but it could just be the placebo effect. I haven't been back to the dyno since then.

As for proximity to the motor mount... I dunno. The same as every other header, I assume. Why do you ask?

Anyway, here's my graph w/ a comparison before (red line) vs. the run with heat soak (blue line).

Gernby

What I have found that helps a lot on the dyno is to unplug the fan switch, and jumper the wires together on the harness. This will keep the fans running constantly, then hold the revs at ~3K to move the coolant quickly while the heater is set to full blast. I did this while tuning last summer for 6 consecutive pulls over 1 hour, and all my results were within 1-2 HP.

Gernby

BTW, keeping the revs elevated between dyno runs not only improves coolant flow and cooling, but it reduces heat soak in the intake manifold.