Originally Posted by JamesClay
It is a very solid setup. We have labeled these JRZs an Ultra-Premium piece. There are a lot of good dampers out there (and some not so good) and without question a suspension is the best way to make your BMW fast on the track. Our Ultra-Premium lines (for us, JRZ and MCS) not only have excellent and I feel superior performance, but they do it elegantly - huge performance without all the rough edges usually associated with it. Usually with lesser (and typically less expensive, so there is that) setups, you can get some part of the whole improvement, but not all of it: will take enough spring, but feels like you are on a washboard, feels really good and minimal NVH but performance improvements are moderate, or simply just doesn't last because the quality isn't there.
I won't comment on better than 4250 because I obviously have an opinion, but I can say that I think the JRZ RS1 is an absolute top performer, can handle a lot of spring smoothly, and is a very quality, well-made piece that will be extremely durable and last for a long time - and you can rebuild it when it wears out.
Excellent description James