Removing them helps suspension travel when driving off road.

On road, they stop lean and body roll of the vehicle (especially on an IFS vehicle).

When you corner, the weight of the vehicle shifts to the outside, causing the outside suspension to compress. The anti-sway bar counteracts this to a degree.

Removing the rear bar doesn't make much difference in handling (the Frontier doesn't even have one).

Removing (or disconnecting) the front one should only be done off road.

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Regards,
Ian