I would start about 3.5k, when you take off slip the clutch out quickly but not fast enough to drop the revs. When I went to launch I would hit the gas pretty hard and slip the clutch out fast enough to keep the rpms between 3-4k and once the clutch was fully out then floor it. It takes a lot of practice but this way I would get no bog and the turbo was spooled by the time I hit the gas hard.