Here are kits I have made for 928's. One is for 84-86 euro 928 S (twin-dizzy) and other is for 928 GTS (also fits to S4 and GT).
I tuned euro S kit on my personal '84 928 S and it gave huge improvements in driveability (much smoother idle, transitions, throttle response) and also more power. Top end gaine around 14 hp but midrange torque difference was 321 rwNm vs 351 rwNm. Made dyno runs on both LH+EZF and VEMS on the same dyno on the same day.
Here is S kit installed (LH and EZF are still in place so I can easily swap between them on the dyno, now removed).
I used faster responding open element air temp sensor (direct replacement for stock one) for both runs.
