Carrera in the States offer springs in all manner of rates. They are primarily for speedway but can be used for anything. They even list 1200 stuff in their catalogues. Try a supplier to the speedway guys for a list. Carrera springs also come chrome plated and therefore must make your car faster... On the spring cutting issue it's all been pretty much said all ready but I have run them and had no problems , but as a certifier I have been educated in the manner in which cutting a coil spring decreases it's designed strength The maths is mind boggling but cutting 1 coil can load a spring by 30% more and can quickly alter it's safety factor.