Have you had your alignment checked? When I hear jiggly, I always wonder if their toe-in spec is toe'd out too much.Second this. The ride is trash. I have owned plenty of sports cars in the past. With all of them, the ride was firm when the road was bad. Bumps would not soaked properly. With M3, it's weird setup. Big bump;s are soaked up nice, but on normal/fairly smooth roads I get constant jiggly/shaking/pulsating feedback through steering wheel as if it's picking every ultra-minor imperfection inthe road. Does my head in. None of my previous sports car had this jiggly steering feel. I am looking to go down the coilover route as well.