Is the denso brand new? Denso is generally good stuff. BUT!!!! I'm not so tickled with Napa's warranty. I have an account with them and have had for many yrs. I used to buy all my stuff through them. But they always hem n haw when I've taken something in for a legitimate warranty. They ask for the receipt ..and they KNOW I have an account. I think they do that so other customers hear it. I ask them to look it up in their system (my account) ....and it's like pulling teeth. And things like pre-warped rotors I've taken back (I put a dial indicator on any new rotors) ..they very begrudgingly take back. And they just make it seem like I'm taking candy away from a baby. Maybe they're better out at stores in your area. I listen to how they handle other customers's warranties. They tend to make it very tricky or deny warranties w/o proof of purchase which other auto parts places gladly take care of. Now ...maybe NAPA has improved in the last couple yrs. I stopped buying alternators/Starters (and even brakes) from them for the reasons above.
Whereas Autozone or OReilly, you can walk into any store and they practically trip over themselves to look up & get ya a replacement warranted part. No "you're making me work real hard dance" where they ask for the receipt. They handle warranties very professional and courteously. (Better than Advance IMO). I've even complained about a set of brake pads once at OReilly's (had one pad rust off the backing plate) just an off-hand remark while I was purchasing new replacement pads. I didn't have the old ones with me. While I was standing there, he heard what I said, looked it up on his own (to see if I had bought them from OReilly's). Again, I wasn't asking for a warranty. But he handed me the box of new pads and said "These are on us, hopefully they won't rust up like the last ones". I just don't see NAPA every doing that. Not at all. I had a brand new Bosch alternator go bad on me, after 2 or 3 yrs. Autozone looked it up, walked back and handed me a new one, said bring the old one back once you get it off. No questions asked, didn't make me feel like I was putting them out of business, no receipt questions, saved me a trip (it was a difficult to change alt) ...and a smile on their face.
For those reasons alone, I tend to buy most items from Autozone or OReilly's. I'd probably buy the starter at Autozone/OReilly's too if I was in your shoes. What good is the warranty if you have to 'work for it'?? Plus, I haven't had bulletproof luck buying 'new' starters or Alternators anyway.