I pulled the expensive Japanese Mini Delta Fast road springs off mine and put Red Spot Cones all round on mine. I wish I'd done that ages ago. It has totally transformed the car to say the least. I can't believe how much better it is now!
Our roads on the Isle of Man aren't the best, my car now goes over the rougher stuff so much better and the handling is very much improved.
My brother who races his Cooper S and wins races also runs the Rubber Cones and so does my dad who has Tony Ponds old Mini. My brother commented when following me one time that he could see the back end properly bouncing around when going over the bumps. What was actually happening was the spring was running out of travel, then coil binding sending the car bouncing off! Funnily enough it doesn't do that anymore!
Alice Drooper their is a very good reason why springs on a Mini draw "the usual criticism" and that's because they don't work as well as a rubber donut does in the small space available. If you're happy with them fair enough but I'd bet my own money that if you put a fresh set of Red Spots on it would be a heck of a lot better.
Kevinmini I'd recommend that you do a search on these forums to see what the general consensus is regarding fitting springs to a Mini. Basically not recommended! Do yourself a favour and stick with the rubber cones. I'm very happy with the Minispares red spots.