Katzkin Leather Install - My lessons learned

After reading a lot of successful install stories I decided to order a kit for my 2023 TRD OR. Thanks for John Huey for a great ordering experience and assisting with color questions. Below are the things that I learned that I didn't find documented in other places. Hopefully it helps another person with their install.
I have never done upholstery before and am an average (at best) weekend mechanic. It took me about 16 hours total (broken up over a weeks time) to complete the install. I also added heated seats.

My seats are black leather with frost contrast stiching. I also added the diamond tekstich but had them use black stitching on that instead of the contrasting frost color.





Tools/Items needed:
- Hog ring pliers - I used Harbor Freight 7 1/2 inch straight pliers
- 3/4 hog rings x 100 is enough (purchased stainless steel rings on Amazon)
- Needle nose pliers
- Plastic pry tool such as an interior trim removal tool
- Small bolt cutters - I used Harbor Freight 8inch bolt cutter.
- e14 external torx socket
- Various metric sockets
- Philips screwdriver (magnetic recommended)
- Small slotted screweriver
- Large slotted screwdriver
- Razor blades or sharp utility knife

I found these three videos to be very helpful. I suggest you watch all three BEFORE you start the job. The heated seat video is valuable even if you arent installing heated seats because it covers some aspects of the leather install that were not covered in the other 2 videos. I also used these as a reference along the way during my installation:
Part 1: https://youtu.be/apVyaDq2-Jw?si=xDgBe5OHhtp48ZMC
Part 2: https://youtu.be/SNZeRrf6BHc?si=jt1HK9X5XqH9dIYe
Heated Seats: https://youtu.be/NknJzVGi60Q?si=yxep251DSe6vKWjV

Here are mistakes I found in the above videos:
- Do not make slits with your knife for the hog rings. The pointed ends will make their own holes.
- The proper tool to take the side airbag out is a e14 torx. He refereneces the wrong size in one of the videos
- When pulling side plastic covers from the front seat bottoms pry straight out or clips break.

Other items of note:
OEM Headrest covers do not come off. The new leather goes over top. Turn the leather turn inside out and roll them down over the top. Be careful when pulling on them as the seams can rip easily.

I did the rear seat bottoms frrst, then the rear seat backs. These are easier then the fronts and allow you to get the technique down.

Cut the slits for the headrests WAY smaller then you think. I cut an X and then pushed the leather around the plastic holder. Take your time here and go slowly on the first one. I used a new razor blade for each one.

If you have a power front seat move it all the way forward before removing it or else you won't be able to access the screws to remove the upholstery.

I used a garment steamer to get some of the wrinkles out. This worked ok. I am also told that the summer heat will tighten the seats and I have seen this is action as the weather has warmed up here.

If installing heated seats, read the instructions. My heating elements (provided by John) were different then many of the others I had seen in posts and videos and had very specific install guidlines.

If installing heated seats, make sure your heated seat wires are running out of the back of the seat and accessible before hog rings are installed. They can shift while installing the covers and are a bear to get to if you dont notice this before clipping everything in (ask me how I know this).

My vehicle didn't have heated seats but was pre wired from the factory (as many of the later model years are). All you need to do in install a

$10 Denso 5670001 Relay

Denso 5670001 relay into the factory location to make the wiring active. The factory location is just above the kick panel on the drivers side under the dash. In my case the fuse was already in place from the factory as well. This will give you an ignition switched hot on the factory connector under the driver and passenger seat. The wire is on the main harness under the seat. It is sky blue under driver's seat and dark blue under passenger seat. I used a ground located under center console cover. This method prevents you from having to install a tap into the fuse panel or run a cable to the battery as it energizes the circuit that Toyota intended to be the heated seats. I cabled up the seats are per the instruction provided with the heated elements and used the switches provided with them as well. Follow the instructions given with the kit. Connect the hot and switched hot (you can tie them together if the kit has both) of the seat to the factory sky blue (drivers side) or dark blue (passenger side) wires under the seat.