So far the only noticeable difference in boost treshold, response (lag) and precision come from dual-chamber wastegate control, where upper chamber is controlled by electronic boost solenoid (which is controlled by ECU or EBC).
We have tried both stock 930/931 units and Tials and to be honest never seen any difference other than Tial being lighter.
With stock unit boost is absolutely steady and both chambers are perfectly controllable. No spikes, creeping, fluctuations, nothing!
My Gulf race-car runs at 0.8 bar base pressure which is adjustable with a knob that sends 0-5V signal to ECU (VEMS) which controls the boost solenoid and I can turn it up to 1,5 bars.
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'83 924 (2.6 16v Turbo, 530hp),'67 911 hot-rod /2.4S, '78 924 Carrera GT project (2.0 turbo 340 hp), '84 928 S 4.7 Euro (VEMS PnP, 332 HP), '90 944 S2 Cabriolet
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