Looking to find a good sway bar to pair with Greene coilovers. 7K front spring rate with 8K rear. I know that the coilovers will affect oversteer/understeer and I don't want to go so large that I have crazy oversteer. What size should be neutral? Recommendations?

 

19mm........especially when you get the camber dialed in. 22mm is too big.

 

22mm is the most popular. I guess people perfer it to be a little most stiff. But 19mm/20mm is what I like.

 

I'd go with the our comp bar as we have found it idea for the R53 and I'd set it on the middle setting. It's a hollow 25.5mm so it's the same stiffness as a 22mm but not the weight and the bushings on it are reliable.
https://www.waymotorworks.com/wmw-rear-sway-bar.html

if you do go 19mm we have them on sale, I feel you end up wanting more rotation though.
https://www.waymotorworks.com/h-spor...-bar-19mm.html

and free cont. US shipping on orders of $120 or more

 

Is there a point in upgrading to a 19mm bar when I have an 18.5mm bar on the JCW? Will there be a difference? It'll be adjustable sure, but are the arms shorter as to make it stiffer with same diameter? Can't find specs on the JCW bar vs. aftermarket 19mm bars.

 

19mm bars will have stiffer settings as they have additional holes to attach the endlinks to. So they can be stiffer than the JCW bar.