Looking to buy a new 2019 Mazda 3 Touring sedan with 6-speed MT (AWD if they decide) when they become available. What handling mods can be done without voiding the warranty? Is warranty dependent on state (PA in my case)?
Improving handling:
1. New tires (depending on OEM quality)
2. Upgrading suspension via front & rear adjustable coil-overs and camber & caster plates all to help with lowering the car, stiffening your suspension, and adjusting camber.
If this car is for daily driver would coil overs with stiffer suspension be annoying when commuting in bumpy city traffic conditions?
3. Front or rear sway bars depending on stiffness of the suspension and to reduce over steer/under steer.
4. Angle kit mod (small chance this will be done). Should this be done at the same time as coil overs?
Any recommendations on brands and specific upgrades would be appreciated.

Performance HP & Torque:
I believe the new Skyactiv-X 2.5-liter 4 banger for 2019 model should suffice with roughly 185ish HP and 185ish lb-ft of torque.
I don't think CAI combined with Catback exhaust and proper tuning is worth the 15-20 HP increase at best for realistically $1400-$2000. Not to mention definitely would void warranty. Thoughts?

 

Other than tires, there really isn't anything you can do which will materially improve handling or performance. Mazda has sorted the car out very well.

 

You honestly will be pretty amazed with the ride of the vehicle stock compared to the 2018. It got me to buy one.