This was the first upgrade on my 2001 9-3. I found the instructions a little unclear, so I stopped worrying about following the procedure to the letter and followed my intuition instead. Fortunately, it's pretty hard to screw up the installation. The results were dramatic -- a great sound and a tangible bump in performance. I would say on the performance side, it didn't change the behavior (shape) of the torque and power curves, but gave a slightly higher peak. That's completely subjective, however...

Definitely a worthwhile upgrade.

Rating: [5 of 5 Stars!]