Warranties are for pussies.
LOL
I'm torn on it personally. I used to be a dealer tech for Mazda, even worked for Ford for a bit, and having those ~5 years of experience in a non shade-tree environment has left me with plenty of skills to work on my own car so from that perspective, I'm not scared of losing my warranty. That said... I can fix my own car, but I don't want to pay for it, especially if it is truly caused by a defect and not my mods. The only things I'm not comfortable with anymore are internals, but if it isn't in the engine, I'm good. Clutch? Got this. Full engine swap? Sure, rent an engine hoist and handle it, no problem. Now that I don't do it for a living I actually rather enjoy it again, but I really don't enjoy paying for it.
The problem is even if a defect caused your issue, chances are high that if you're tuned and they know they are going to deny your claim and say you have to pay it. Yes, yes, I know all about the MM warranty act, but the thing is they can deny the claim and put the ball in your court to pursue a legal battle and that can take a long time. If you should happen to lose? Well now you're out the cost of the repair and the legal fees, and they might even add more onto the cost for the extra diagnostic time it took them to fully determine the cause as your mods.
I do NOT expect a manufacturer/dealer to pay for breakage that I did in fact cause. If I decide to run 35psi of boost and melt the engine, that's on me and I would never expect them to pay for it since I'm the moron that did it in the first place. The problem is all in the dealer mindset to immediately blame the mods. This is why I'm so heavily considering the MP215 kit instead of buying just the AP from Cobb or Mountune with their respective maps. It's a lot more expensive, and you have to pay someone to do piss easy work, but it does keep that warranty nice and fresh.
What I've considered doing is putting money aside every month, like $100-200, and call it the "warranty fund". This way if I do grenade my engine I have a stash to pull from to pay for it and if I don't, I can keep the money for the next car I mod, or use it as a down payment or something. Also, if I don't go MP215 I think I will buy my AP from Mountune since you get a Randy tune to start and 45 days of support for remapping based on your data logs and that is a helluva lot better than a canned OTS map for the same price, in my opinion. Especially since the Mountune bought AP includes Cobb's stuff too if you want to use them anyway.