I've got an old 80's insert that's installed slammer style currently, and I'd like to get away from that setup within the next 2-3 weeks by going with a full liner inside my existing terracotta flue. Flue size is 11 5/16" x 6 5/8" ID that goes down about 15' to the smoke chamber, from there it's about another 5-7' feet to the insert itself. The damper plate is 6" x 24" and I plan on making a block off plate, notching it just a little for the liner and stuffing the smoke chamber with Roxul. Roxul would also be used for the top and bottom insulation in the existing flue and any extra I have I just might push down further in the flue to help with insulation. That brings up a question, it's a ~20' length chimney that sits on the outside wall of the house, but the garage is enclosing the lower ~12' of it. Draft has never been a problem with my current setup and I'm not sure if it's worth the cost of buying a liner insulation wrap. I've been looking at the Flex King PRO 6" x 25' for ~$500 and the Homesaver Ultra Pro for ~$420. Does anyone have any opinions or experience with those liners? I like the fact that both of those allow for the warranty to be honored if installed by the homeowner, and that's why I had focused in on those two. I think the chimney is in pretty decent shape, and if anyone wants to take a peek at some pictures of what it looked like after a light cleaning, they're a few posts down in this thread: https://www.hearth.com/talk/threads/project-old-non-epa-stove-slammer-install-looking-for-advice.103780/ Thanks in advance for any advice you've got for me!