had my manifold changed to a high flow one on my s3, and now the steering wheel is vibrating when ever sat still. Basically like a bus lol. I know that they dropped the subframe when changing it could they of put it back incorrectly. And what could be causing the vibrating could it be the down pipe. Btw it's the v4 pro manifold and the down pipe is the pipeworx 3" with decat.