That's why the suspension manual only gives the spec for "nose down" in relation to the drive shaft. Because if you get that angle right and the spring perches are right, the rest of it falls into place.....at least on a Mopar. Suspension manual says 5-7* for a race car and 3-5* for a street car. I forget what the spec for the spring perches is, but it's all in the suspension manual. Mancini sells copies for 10 bucks. Get you one.