I've used ross in the past. My last L I built was in my zx in NA form except the last 5k miles before I sold it. I had it turned up to 10psi on a stock efi turbo setup.
But, the general consensus is that forged are only need in extreme cases or when RPM are going to exceed "elevated" levels. If you're staying below 6500 you shouldn't have a problem. Also it sounds like the rings got toasted, not the pistons, from uneven detonation.
Have you torn the engine apart to inspect?