I have been using HKS ADD-I booster for track purposes. Adding 500ml to a tankful of 97 ron fuel (50-55 litres), the engine runs much smoother and quieter. I can't feel any difference in top end power (it surely does not make my GTR faster) but the low end response is so good I am hooked! Drive at 2000rpm in 4th or 5th, then mash the pedal hard and the car just smoothly go to 8000rpm without complaining. Try doing that on normal fuel and the car would drag itself like a marathoner on an uphill run! At 7000-8000 rpm on the track, I could hang on to that rpm for a long time without the engine running out of breath or huffing and puffing. The expense would prevent me from using it everyday (USD 27 per 500ml bottle!) but for track days and high boost (1.02 bar) I would never do without! Try it, you will never regret it except for the fact that you would feel the engine is much louder/coarser and less responsive without it! That's a curse!
