most of the spring makers are pretty good i have no direct experiance with bbk, only old saggy eibach's, a important part of lowering spring is the other stuuf you put with it, caster camber plates are a must have, and if your struts and shocks are worn out they will not be enough damping for your springs, and the ride will suck(lots of experiance with that). My advice would be to call maximum motorsports, those guys know there stuff and can steer you in the right direction, to lower the car and make it ride nice as well(i just bought their complete coilover kit, and they have by far the best service and support i have experianced in the car industry) also 1.5 is the max you should lower it, any further causes all sorts of issues