ransley unnecessarily full-quoted:

And that warranty goes down the drain, 10 yr extended and lifetime
heat exchanger you loose.

No.

Anyone who buys a new furnace and ends up needing to rely on any sort of
corrosion warranty will lose.

Because as past history has shown, you need to launch a class-action law
suit in order to ever get compensation.

With thinner heat exchangers and electronics, odds are you just
lost your savings.

If you think at the outset that you're buying a piece-of-**** furnace
that's going to break down on you like that, then it doesn't matter
whether or not you've modded the furnace. You shouldn't be buying a
piece-of-**** furnace in the first place.