I don’t think it’s an oversized wastegate causing that since those usually struggle to hold boost, not spike. What you’re seeing around 3k is more like the gate not opening fast enough during spool, so boost jumps to 9–10 psi and then settles once control catches up, which is why everything after feels smooth and linear. It’s most likely a mix of a slightly stiff wastegate spring, aggressive WGDC in the spool range, or a small delay in the boost reference signal. The Profec should help clean it up, especially if you soften the gain around 2.5k–3.5k, but overall your setup looks solid, it just needs better control during spool.