No problem with thr reposting. I wrote that as "public domain" to be shared freely so long as I get all the glory, er, credit.
You're fighting two big issues in the M3 vs. 930 battle.
1. Power delivery. Having tracked 930's before the biggest issue I see is the power delivery. Obviously you want to be at full-on accelleration when you're tracking out to maximize your corner exit speed. Problem is, that means you've actually got to get on the gas earlier than that to allow the turbo to spool up and time it exactly so that when you need to power to come on, it does. That takes a LOT of practice and I never managed to get i right most of the time.
Basically I'd brake, turn it, and get on the power so that JUST before I hit the apex the boost would start coming in. By the time I hit the apex, it would be on full and the car will launch out of the corner. Very hard to do.
2. Suspension. The 930 suspension design is antiquated compared to the M3. Macpherson style struts and the swing-arm arrangement compared to the multi-link is no contest. THere are many things you can do to upgrade it and make much of that go away, but it's still an up-hill battle.
Can you describe your suspension?