So, I emailed a vendor inquiring about custom spring rates for the BC Coilovers I wanted to order. I asked them how long it would take to deliver a "custom" coilover kit and gave them the part number that fits my car. The reply looked like this:

I'm confused. How can something be in stock if it needs to be built? Do they just keep the sets on a shelf and order springs as necessary?

 

Maybe your spring rates are common enough that they stock the corresponding parts?

What chassis and what rates?

 

they may need to be revalved for stiffer spring rates..

 

My BC setups both took around 3 weeks, one was a custom order for my FD2 the other was a custom double adjustable for my EK9.

 

My 10k/12k Swift spring BCs shipped right from Taiwan. Did you email their FL office? They don't stock all the rates there, so my guess is that they happen to have a set of your model number in stock, and it either doesn't require revalving of the damper or they have the ability to revalve the damper, and they have the rates you want.