Need help with suspension calculation

I'm trying to figure out the spring rates required for my car:
1988 325ix track prepared (2.25'' springs, BBK, caged, turbo, slicks)
Weight 3050; 55% in front.


I'm using some online formulas, like the one on Eibach website:

http://ift.tt/1OAptaA

When I get my rates, I google what others have installed on their E30s and Z3 Mcoupe, and ALL, according to the formula,
have springs that are too stiff at the front. According to these people, their car has a neutral handling. They should understeer
due to the stiffer fronts, so I'm confused.


Right now, I'm running 550F/1000R without swaybars, which, compared to other E30 users, is way too stiff at the rear.
As is, my car rotates well, and is not twitchy. Only a bit 'nervous' in tight corners.
With my calculation, my front wheel rate is near 55% and the rear 45% so they match the spring rates in percentage.

I'm using a rear motion ratio of R=0.645 and F=0.909 for they formula.

Anybody cares to do some math to check if I'm close or far from what is required, or explain to me why my setup is so far
from others.

Thanks.

Need help with suspension calculation