Well, it's not compressor surge with the stock turbo under those conditions... I would suspect, in order, bad maf, bad coil pack/ign. module, or equally suspect, fuel pump.... even though you are showing 810 mV on the SM, it is slow as hell, and can't display the instantaneous O2's like directscan or powerlogger can... it is only giving about 1 frame of data every 1.5 seconds... vs. high speed data, 20 frames/second... car could be dying lean and recovering (causing the compressor to snort and fart and make all kinds of racket), all under the SM's nose.....
also you never stated 'it's normal pressure'..... what is the base fp, and what chip? Verification of the fuel pressure/rise-ratio is MANDATORY.... even more so with your initial worry about only a 2 psi rise line off, and slow at that.... :wink: