2005 SLK 350 Sport
I put a pulley on and under 3/4 acceleration it went to 7.9lbs of boost and misfired. On comes the check engine light. Took the pulley off and sent it back to the manufacture and it turned out it was 5 grams out of balance. They rebalanced and sent it back. I had it reinstalled and this time the motor idled a lot smoother but under 3/4 acceleration it went to 7.9lbs of boost again and misfired. I replaced the fuel filter and all four ignition coils. This time under 3/4 acceleration it went to 9-1/2lbs of boost and pulled stong with no misfire. The coils made a big difference and I'm sure the fuel filter didn't hurt either.