As Jgti-r says his Whiteline are hard....and I know that the Whiteline spring rates are no was near the 5Kg to 7 Kg.
My personal opinion are that 7 - 5kg spring rate is WAY to high for a normal road car
.(would be ok on a smooth race track)
One of the best handling cars on the road are Lotus and they never ever fit hard springs, they sort the suspension out in other ways, like roll bars, camber, shocks, anti swat and dive etc.
Just fitting hard springs is not the answer to getting your car to Handle.
Its a mind boggling science, read books by Alan Staniforth this will explain it in full detail....does your brain in to. :roll:
I know this all sounds bad news but like everything else it takes time to get right, been working on mine for all of this season to get it right.
I have beating cars like 911 RS's BMW M3.s, Evo's, Scooby's and numorus TVR's this year on the track and still only have a normal untuned engine. So I think i am getting there now. :lol:
If mine was just a road car i would use the Teins with the normal springs they supply, they are pleny hard enough, or even Koni inserts and Whiteline springs. Then fit all the handling kit, poly bushes etc. This would be a great road package. Also a resonably ride to.
Hope this helps.
Cheers
Phil
PS I am an old bu gger been racing for over 20 years so have made plenty of mistakes myself in that time. Its all a bit of trial and error.