hi guys, i've heard of coupla good reviews on the ZX1 additive. My mate uses it in his VTEC engine and claims that he can now rev to 9k rpm without the harshness from before.
what do u guys think?? is it advisable to add it to an already good engine oil (castrol RS 10W-60) and to the gearbox for smoother shifts and less drag (more horsepower)??