very easy to fit, normally only 5 bolts, 2-3 14mm on top of the strut then 2 19mm bolts on the hub. if i were you i would try and set the coilovers to an even hight when installing them(less messing around later).Also when installing make sure you push the hub inwards to run negative camber untill you get a wheel alignment.
normally a good spring rate is around 8-9kgs. i had 10kgs front and rear on my silvia. that was a drift car so it was very stiff. if your car is a daily driver and only raced every now and then 8-9kgs will be fine. you should also look into getting some sway bars aswell

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Marti


Car: C Red S13 Silvia 2.3l 400+rwhp-SOLD
Daily ae82 4age corolla (light mods)-Sold
Daily:SWB GQ Patrol
Will be a 03-04 STI next