the drivers side so I had to remove the shield on it. As for spool up, not that bad. I get full boost at around 5k. With tuning on the dyno, I am sure I could make it less if I play with the timing. Considering I was getting full boost on my TDO5's at around 4500 I could live with it. The rush is increadible when the TD06's hit and it sounds like a jet.