Asif it's not as simple as what is better for road use there are so many variables to discuss it's untrue, if you want to slam your car then get some D2's, there okay for the money but far better out there. If you want something you can install from day one without setup and be confident they are good for the road and the occasional track day then get Koni, they don't boat at all very stiff just more forgiving with the rebounds. If you have £1000.00 to spend then get some high quality coilovers, customise the spring rates to your setup and get them setup, let's face it if you have a grand to spend on coilovers another £150.00 to set them out isn't going to make much difference.
I've tried D2, K-Sport, Tein Flex, Super Streets, Buddy Club JR, Cusco Zero1's, Ohlins fixed rate with Ohlins springs, Koni with WL, Koni with Tein, Koni with RS*R, Koni with Ventura, JIC Pro specs, Tanabe S something and god knows what else really have been through a lot.
Coilovers have a stigma with them, I always here there too hard but everyone forgets coilovers are the same as shocks and springs they are just complete units, nothing more nothing less they are the same which ever way you look it, coilovers are still shocks and springs. It's the fact that most coilovers come with unsuitable springs that make them shit for the road nothing else, most people will just buy them and slap them on without knowing anything about the rates which is why they have a stigma.
You get what you pay for at the end of the day, Koni may be near the price of D2's but it doesn't matter, Koni designed the Ford GT40's suspension they have been around for 50 years, D2 are just a random Asian company that just used an old design and copied them they don't have years of research behind them, despite this for the money there not bad but yes there are far better out there. Look at the Ohlins Type C setup for the Starlet, these are separated units i.e. not coilovers and they cost £1500.00 which is more than the most expensive set of Starlet coilovers.
Coilovers are shocks and springs, imo for UK roads anything over 5kg and you'll be flying over bumps rather than driving. You can customise the rates on shocks and springs just like you can with coilovers, one advantage with coilovers is most come with pillow ball top mounts but some of the designs I have seen are pretty poor. If you are prepared to be patient, work out what rates you need, get them setup properly including corner weights, camber, castor, toe in/out then yes you can get a great setup with coilovers. If you are unsure on what you need, can't be bothered with setting them up and want something you know will work well and won't need a lot of attention then a shock and spring combo like Koni/Ohlins will be very good.
You can't ever perfect a coilover setup on the road, there are too many variables with road condition you would need to have a pit crew follow you every time you found a slightly different road, units like Koni and Ohlins have been designed with roads in mind hence they are more controllable, yes they won't be quite as quick as a coilover setup perfected for the track on a smooth smooth well prepared track surface but whoo drives there Starlet on the track only?
The choice is yours...
T
