I had an M45 Eaton Blower on my '99 Miata. I ran 6 psi and it was good for an additional 60 rwhp. I had the car dynoed before and after so it was a factual increase. It had pretty good drivability with just a little idle droop coming to a stop when cold. It was a Jackson Racing kit, ok quality and used a "black box" to fool the ecu into thinking it was 50 below to get the needed fuel. Also came with a cam angle adjustment bracket to pull out enough timing so the thing wouldn't ping like crazy. I could run with S2000's at the track with it.