If anyone else cuts they're own springs - be very careful - the metal comes off easy but it's a bit*h to put it back on!! I've owned something over fifty cars (I stopped counting) and lowered alot myself. It's hard to describe that feeling when you drop the jack and it won't come out from under the car! I've found if you climb under the car with something to measure the "loaded" coil to coil distance then you can extrapolate from there the approximate amount of drop measured in coils or partial-coils. That's pretty rudimentary, and doesn't take into account progressive rates and the amount that the spring will stiffen when you shorten it but... It gets you into the ballpark. If in doubt take less, put it back together and measure - taking care to roll the car back and forth to make sure the suspension has settled. I ended up with one full coil in back and a half coil in front, within an eighth of my calc.