Almost all street cars come from the manufacturer with an anti-roll bar as it is a common part of modern suspension systems. However, they are designed to be overly soft for maximum comfort. An anti-roll bar does exactly what it says by reducing body roll in all situations. Every Dinan tuned anti-roll bar is built and tuned specifically for each BMW chassis. Lowering the amount of body roll keeps your BMW more level than stock (while still allowing just enough body roll) to improve mechanical grip. This improvement gives the driver a much more planted and confident feeling in every corner. Front Anti-Roll Bar Add a 28mm Lightweight Tubular Adjustable Front Anti-Roll Bar to reduce body roll to improve grip and stability while saving weight at the same time. This anti-roll bar is adjustable up to 45% to 97% stiffer than the stock bar*. This 3 hole bar can be mounted in 3 different positions with stock BMW end links. *Stock bar is 22.2 mm on the M235i/M240i which means the new bar can be adjusted from 45% to 76% stiffer than the stock front sway bar. The stock bar is 24.2 mm on the 328i/330i w M-Sport which means the new bar can be adjusted from 50% to 81% stiffer than the stock front sway bar. The stock bar is 21.2 mm on the 335i/340i/435i/440i which means the new bar can be adjusted from 63% to 97% stiffer than the stock front sway bar. The stock bar is 22.2 mm on the 335i/340i/435i/440i w M-Sport which means the new bar can be adjusted from 54% to 87% stiffer than the stock front sway bar. Rear Anti-Roll Bar Add a 19mm Lightweight Tubular Adjustable Rear Anti-Roll Bar to reduce body roll improve grip and stability while saving weight at the same time.This anti-roll bar is adjustable up to 84% to 474% stiffer than the stock bar*. This 3 hole bar can be mounted in 3 different positions with stock BMW end links. *Stock bar is 15 mm on the M235i/M240i which means the new bar can be adjusted from 84% to 130% stiffer than the stock rear sway bar. Stock bar is 12 mm on the 335i/340i/435i/440i which means the new bar can be adjusted from 359% to 474% stiffer than the stock rear sway bar. Stock bar is 13 mm on the 328i/330i/335i/340i/435i/440i w M-Sport which means the new bar can be adjusted from 243% to 329% stiffer than the stock rear sway bar.