We really couldn't have said it any better than MPP so please read this excerpt from their website below. They do an excellent job in explaining why bigger is not always better and why anti sway bars, when coupled with coilovers, should be a final tuning tool rather than a primary one. Quite often we see clients starting with stock or lowering springs that add anti sway bars to mitigate some of the roll they experience. Then later down the line decide to upgrade to a coilover, which naturally has a higher spring rate, but now the sway bars are over compensating for this thereby reducing compliance and grip. We love that MPP has produced a sway bar that is truly designed to work with a coilover suspension system. It increases stiffness in minimal increments and your softest setting isn't overly stiff versus most other aftermarket bars. Enjoy the read below:

Link to all our anti sway bar offerings is below.  Direct link to the MPP Anti Roll Bar is at the bottom of this page.

https://zevcentric.com/collections/sway-bars

CREDITS:  Mountain Pass Performance

Sway bars. Or, as we call them, Anti-Roll Bars. At MPP we’ve always taken the position that sway bars for the Tesla Model 3 were a minor item – and that the main area of improvement was in the springs and dampers. Hence, we’ve spent the majority of our effort developing our Sports and Comfort Adjustable coilover kits for the Model 3. However, we’ve had a number of inquiries for aftermarket sway bars that had a wide range of adjustments, and that didn’t cause unwanted noises or contact with other suspension components – a complaint that we often receive or diagnose from customers who think MPP parts are making noises!

After testing a few different available bars on the track, we quickly realized that sway bars that are too large can result in unwanted snappy behavior, where one axle suddenly loses grip. We were left with a car that had excessive understeer on entry, which transitioned to snap oversteer on exit. Installing the OEM sway bars on the same day at the track instantly solved these balance issues. This was likely more of a compatibility issue with MPP products rather than an inherent flaw in the aftermarket sway-bars, but it solidified our opinion that overly large bars, which have the effect of coupling the axle, were not needed for a car with such a low center of gravity.

The result of our testing is our MPP Adjustable Sway Bars for the Tesla Model 3, which at the softest setting are similar in stiffness to the OEM bars, but offer a range of tuning that can be used to fine-tune the balance of your car for your specific driving style and wheel and tire setup.

 

Design:

We’ve voiced our opinion that the best way to get rid of the body roll from the Model 3 is through increased spring rates, as the low center of gravity provided by the battery pack results in very little body roll relative to the spring stiffness. The increase in spring rate is needed because driving the car aggressively with a fairly low ride height can lead to bottoming. So the problem isn’t related to roll as much as it is related to the vertical motion of the chassis – which is called heave.

Sway bars do not influence heave, and as such, they are a good tool for vehicles that have a lot of roll and relatively soft springs. The downside is that sway-bars move the vehicle in the direction of a solid axle – the two wheels are connected via the swaybar, so road irregularities that affect one wheel will transfer and also affect the wheel on the other side of the axle. The OEM Model 3 Performance already comes with fairly large sway bars compared to other similar cars, so the concept of just making them larger really needed to be investigated.

The first thing that should be mentioned is that sway bars are not mandatory. In fact, the SR+ car does not use a rear sway bar, nor does our record-setting 800 horsepower Time Attack 350z. Sway bars should be thought of as a tool to perform a job, and bigger is not always better. In fact, a common mistake with aftermarket suspension tuners is fitting springs, bars, and dampers that are too big or too stiff, which reduces compliance with the road and removes total grip while also making the car more “edgy” and harder to drive at the limit. This is exactly what we experienced during testing on the track with large aftermarket bars.

Once we tested our solution on track it was clear that we were headed in the right direction. Our recommendation continues to stand that if you want less roll – install stiffer springs. Use bars for tuning the balance, and don’t make them too big!

We have been prototyping our bars for over a year, over a few thousand kilometers of driving. A common issue with anti-roll bars is bushing play and noise, so we wanted to do some real-world driving to ensure the bushings would not be an issue. There are no noises to report, so we’re hopeful the bushings will survive the life of the car. Although, it may be required to re-grease the bushings down the road, something to keep in mind.

The bars are made by Eibach, and we’ve requested features be added such as a 3-hole adjustment in the rear, and locking rings to prevent the bars from sliding side to side – an issue we observed with other aftermarket bars during testing.

 https://zevcentric.com/collections/sway-bars/products/mpp-sway-bars-front-and-rear-kit?variant=44009517154549

Specifications:

ARB Stiffness relative to OEM:

• Front (from soft to firm): +14%, +21%, +28%
• Rear (from soft to firm): +9%, +18%, +27%

Color: Powdercoated silver (which matches MPP blue beautifully!)
Diameter: Not disclosed
What’s Included: Front + Rear bars, (4) bushings, (2) rear brackets, grease