Sway bars are normally solid bars not hollow tubing. I think only tanabe makes a hollow sway bar. My current endlinks are solid spherical rod ends too. All a sway bar does is transfer load from one control arm to another. The less the bar is able to twist the more anti-roll you have. Spring rate is entirely different thing.

And thats why different set ups require different techniques. Most auto-x guys run the biggest bar they can find and the remove the rear.

You dont match the bars to you're spring rate that is just flat out wrong, if you did anyone who changes out springs would have to match their sway bars to it. Shock spring rate and anti-roll are two different things though you can calculate the over all spring rate of the suspension which involves both plus the tires.

Also those poly bushings that are supplied with every kit are resistance to your sway bar, allowing the sway bar to rotate more freely makes them more efficent. Also I'm able to put a certain amount of pre-tension on the bars themselves.

And I enjoy making things and seeing them work the way I planned almost as much as driving my car. Fabrication is one of my hobbies.