First of all, I didn't make the "delete this post" comment...but, you did for mine in post #24 above.
Power is relative...like I said, the EGR does not function above ~4500 RPM, so there is no effect on total HP the engine produces.
The EGR was designed to do two things:
1) To lower NoX emissions...it does this by lowering combustion temps.
2) To raise the threshold where detonation occurs so timing advance can maximized...it's "free" octane.
Everyone seems to focus on the emissions function and ignore the anti-knock function of the EGR. Your conclusion is a result of looking at it this way. You run a USDM TCCS and you are asking for detonation under part throttle/high load conditions. I'm not pulling this out of my proverbial arse:
164 pages on nothing but how the TCCS works on this car
A piggyback will help with the fuel side, but not timing. The solution is to run a JDM ECU (you have to disable speed cut) or go with a standalone EMS.