My brakes are weak initally. The service tech thinks the brake booster has a vac leak. Makes sense. I'm wondering if that vac leak would cause my car to turbo boost improperly such that I could run rich or lean. I ask because at mid and high throttle under high load my car will knock or studder. The car hasn't generated any error codes, and I did replace the spark plugs thinking that one of them may have been misfiring.

Anyone have any tips or advice?

Thanks,
Michael

Just got the Bilsteins installed... yeah. And a new replacement 3"dp w/race cat....zoom.