And therein lies the rub. We're all TWEAKERS!!! In my case, I spent about a year or more getting my Impact to shoot slugs and ended up with the NSA 43.5 at 890 fps, super accurate at all ranges out to 225 yards. (700mm Slug A liner, Ernest xfer port, power plenum, NSA pin probe, lighter valve spring).
But Nooooo, I couldn't let well enough alone, even though I shot a 238 on an EBR target with it at 100yards. So, I upgraded the reg to a high-pressure Huma (I was at 135 bar) so I could go to 155 bar. I also added the Tungsten hammer weight. And tensioned the barrel.
And with all this, the accuracy, ease of shooting, and consistency went downhill. Plus, my shot count went from 40 to 28 shots per 250 bar fill. I had convinced myself that 90 FPE was better than 80 FPE, and that 950 FPS was better than 890 FPS.
And I wondered, where did the Impact go that I liked so much...??? I also shot NSA 38.9 at 990 FPS, but that was no better. So now I'm pulling off the barrel tensioner, removing the tungsten hammer weight, lowering reg pressure back to 135 bar and tuning for 890 to 900 fps in the hope that I can reclaim what I had.
All I can say is - speed and power aren't always your friend, and ACCURACY TRUMPS POWER EVERY TIME!!!!