[VR Baron]

You shouldn’t have an issue if you have the spring rates that are with the kit. I to have never heard of negative preload. If anything preload is positive, you are adding load or putting tension on the springs so they don’t move at full droop. For us laymen the instructions don’t even say where 0 preload is or how much tension is 0.
Off the car I just tightened up the spring perch till it was hand tight to get a baseline or 0 preload. On the car it was like 2” plus lower then stock for me. On Pedders coilovers 0 preload is like hand tight , so that’s what I did with the Ridetechs. Then just set the height to what you want. Kit is designed for 1.5” drop, maybe 2”. Lower then 26” rear hieght (1” drop) can cause axel boot splitting and broken axel if you race the car.
Stock for me was 685mm front, 690 mm rear from lower wheel lip to wheel arch top. Don’t measure from the ground, won’t be accurate. If car is to low ,The fronts you tighten perch upwards, on the rears your tighten downwards. I made mine 1” drop for best handling . Your springs should be fine if you have the 275/500 ones that come with it. I have 300/550 for autocross. I got my set from JDP and they sent me a taller rear lower perch for more travel. But still don’t see why you have an issue.