Front Anti Roll Bar
Diameters available : 5/8” , 11/16” , 3/4”
For fast road the 11/16” bar seems to give the best overall balance when used with 360 or 400lb front springs. In testing a lightweight roadgoing Sprite on 175/60 Yokohama with 400 lb springs going to a 3/4” bar introduced notable understeer.
If you are competing on rough surfaces (autotests/rallying) then a narrower bar can be a better option, as generally you are looking for weight transfer to the outside loaded wheel to aid turn in and reduce understeer. This also seems to apply to some hillclimbs where the front tyres don’t get up to temperature.
It’s an easy and relatively cheap thing to change, so experimenting with your own car to find your preferred set up can be very rewarding.