My thoughts, if you finance you may not be able to afford a major failure. So the amount of $1100.00 added to the monthly payment isn't so bad.
Is the warranty offered manufacture backed or third party, big difference when the dealer submits a claim.
You need to be fair as an owner, you want to modify beyond the original design....awesome! Why would would that be a warranty consideration?
My story about ext wtty. I purchase a fancy $2500.00 plasma flat screen from Samsung & opted out of ext wtty. Less than 2 years catastrophic failure of the screen......2k for the repair. I did not repair & called Samsung, explained I opted out of the ext wtty & would accept partial responsibility for that. They told me "sorry" & nothing they can do, no split the bill, no we not will cover the parts, no we will not offer a discount on a replacement, no nothing......piss off. It was important that I notified them of the LG replacement we purchased, the LG washer dryer combo & various other items. The Samsung dumb phones are next
Like everything, no right or wrong answers, what is best for you?