Does anyone know the stiffness difference between the HSport and H&R 19mm rear sway bars?

 

I got this info from H-Sport. The 19mm / Sport bar = a 17.5 solid bar. If you have an stock sport suspension + set up go with the 19mm H&R. If you have JCW or coilovers or stiffer susp set up try an 18mm H&R. Tire rack had them on Blow Out Price of $89 from what I remember.
Just my $.02 cents.
We have an 19mm H&R on the soft setting w/ 215/45-17's w/ 35psi front & 30psi rear and it works great for us. Slow before the corner and accelerate thur it.

 

Would the 18mm H&R benifit a sport suspension?