Especially if you have a chipped ECU. For example, SZ's Base Tune was trying to set an idle at 900. I didn't know this, so I tried to set it to 650RPM (to get to 750 RPM) per the Z32 Wiki guide: [ http://z32.wikispaces.com/Idle+Control ] . The result was that to achieve this, I had turned the idle adjustment screw too far in, which wouldn't allow the idle control to recover fast enough on a decel, so the RPMs would drop like a ton of bricks and the engine would die on decelerations.