the question that you are asking has been asked a gazillion time since the inception of this thread, the straight forward answer to you is this; "if worry about warranty don't mod, if mod then don't worry about warranty".

sound crude but it is the reality. only a one-on-one replacement of "wear and tear" parts will not void the manufacturer's warranty. modification that only affects the appearance of the car will definitely not void it and generally anything that affects the car's mechanics (even rims sizes / suspension) can be taken to have voided it.

you may encounter some smart-arses throughout the course of your ownership claiming that modifications will not void the manufacturer's warranty but in reality, they either could not be bothered with the manufacturer's warranty or have no idea what the topic is about and and their source is #dudetrustme.

if you are still determined in modding the car after all that is being said, your best bet would be to only do reversible modifications and keep all your stock parts with you so when you need to submit a claim for manufacturer's warranty, revert the car back to stock temporarily but there is no guarantee that the SC will not catch it. this is true for most owners who have replaced their tires with 19's and kept their stock 18's with the tire shop.

Posted this in the cx30 tread as well, but thought of getting more feedback from Mazda 3 owners before we decide to purchase.

Me and my wife deciding to get either CX30 H+P or Mazda 3 Ignite (more inclined towards the lift back). Wife prefers a smaller car cause it is easier for her to handle, else I would have gotten a CRV for space. Anyway, below are some of my concerns:

CX30
1) Wired Apple CarPlay, don’t want to keep plugging our phone everytime we drive it
2) CKD built quality, saw quite a number of post in FB but surprisingly don’t see much complain / issues / warranty claims on Mazda 3’s CBU built
3) tight rear passenger space

Mazda 3 ignite
1) lesser visibility for driver when compared to cx30 (also because it sits lower)
2) don’t have Adaptive LED headlamps
3) very tight rear passenger space
4) don’t like the red burgundy interior
5) not easy for elderly to get in / out of rear passenger seats

Both CX30 and Mazda 3
1) 2019 model with Mazda probably launching a new generation CX30 / Mazda 3 soon
2) no touch screen when using Apple CarPlay
3) I would consider both as a driver’s car instead of a family car. We got plans for family, hence using a rear facing baby seat could be a challenge

Feel free to highlight if my info above is incorrect or if any owners with first hand experience have been through any of the above or have any feedback, would greatly appreciate your info.

Thanks