I take it these are for running the rear spring in the stock location vs coil over n the rear.
We tend to run very still roll settings...esp up front and softer rates.

I hate the whole kg /mm vs lbs / in conversion.
Anywho.....after doing the math..I can see the swifts are popular.. better feel on the track.
Again its going to depend on the other factors in each of your equations....esp roll stiffness.
Running a true coilover in the rear we typically run a split of 250-450 lbs... stiffer on the front spring.
This is with our front bar full stiff.....and our rear bar is fairly soft.

So what is the general consensus on these swift springs on a Nismo? I am mostly wondering for just street use, but I want to make sure that I am not "downgrading" from the stock Nismo springs with getting the swifts. Granted I mostly want the lower appearance, but I don't want the suspension to get sloppy afterwards either.

Are the swift springs really "better" than the stock Nismo springs?