Having trouble diagnosing this one. I recently had my engine replaced, same turbo, and have noticed a change in the sound of spool up on acceleration. Instead of a clean low whistle, it sounds muddy, like there is an air leak. The RPMs stay quiet, performance seems OK, but the sound just doesn't sound right, and it sounds distinctly different. I have thought about taking it to my local Saab mechanic, but since he's busy I thought I'd ask here first what might be the case.