H&R sport springs on koni yellows or H&R full coil over kit. Which will perform better and ride smoother

 

The H&R Sports with Yellows will probably ride better than the full coilover kit, but that's only because the Yellows are adjustable so you can try and match the spring rates like the shocks on the coilover kit are matched.

As for performance...that really depends on the driver...the performance benefits of full coilovers over springs and shocks aren't extremely dramatic, and really can only be taken advantage of by experienced high perf drivers (there are always exceptions, but they're rare). Mostly, a driver that hasn't done a lot of high perf driving will get the same performance out of springs/shocks as with a full coilover kit, because usually at that level of experience (where I am right now) it is not that the suspension is holding back the driver, it's that the driver doesn't know how to get the most out of the suspension. It may feel like I am using all that the tires can give me, but I know that if my technique was better, I would be smoother and the tires wouldn't be screaming at me like they do now

 

I don't recall right off hand what the spring rates are for the H&R Sports, but I'm sure that the H&R coilover kit would have a higher spring rate. Generally a higher spring rate will improve the handling of your car, but it can cause your ride quality to suffer. You really need to find a happy medium between ride quality and performance. This is were everyones opinion of ride quality and performance differ. Some people are willing to live with a little bit of ride harshness to have an increase handling performance. But others value ride quality over performance.

Ideally if all roads were as smooth as glass you could run high spring rates, because the roads would not have any pot holes, bridge expansion joints, speed bumps, etc. This is where the compromise comes into play. You will have to figure out what your acceptance level is for both ride quality and performance. You may want to ride with some people that have different suspension setups and see which is best to your liking.

I personally have Eibach Prokit springs, Koni single-adjustable struts and a Type-R rear swaybar. I live in Ohio where pot holes are somewhat frequent, so I wanted a spring that would not punish my kidneys and my spine when I hit a pot hole. But I wanted a spring that would stiffen up the handling. I also drive my car on the track a few times a year, so I wanted a setup that would perform well on the track. The Konis allow me to adjust and fine tune my suspension for the track. The Type-R rear swaybar reduces a lot of body roll and understeer from the car (on the street and the track), without running a high spring rate in the rear which would make the ride quality suffer on the street.

I hope this help you out.