It totally depends on the make. Some folks 25mm are so different to others. Prime example above, the red one is lowered 5mm LESS than the black one yet looks about about 20mm lower!? I think they just stick any old pish on the box. My mates old RST was only 25mm springs yet it was so low it could hardly fit on the rollers..?

My last RST was lowered 60mm and I had no problems with the handling, even with the 18's! God! 18's!! Death to the infidel!