Painless Cirkit Boss 70107 with Rostra heated seats
Just added the Rostra seat heaters after 12 years owning the truck... got em from Geno's Garage.
My set came with the round switches, selectable HIGH-OFF-LOW.
Installing the pads was pretty straight forward, instructions are clear from Rostra. Though others here have suggested installing the pads upside-down, I just installed as directed... adhesive strip side down to the foam. I find they heat up just fine, I can't leave it on the high setting for too long or it's uncomfortably hot.
As for the wiring, I bit the bullet and installed a Painless Wiring "Cirkit Boss Kit" PN 70107, $86 via Amazon Prime.
The kit gives you 7 fused hots, 4 of which are switched 12V and 3 are constant 12V.
It comes with a great set of instructions, but basically there's a hot wire straight to the battery, and a pink wire that runs to switched power to activate the relay that energizes the switched circuits. Then just 7 labeled/colored wires that you run to your accessory loads.
For me, the biggest decision was where to mount the fuse block. I did not want it in the engine compartment, and I did not want to hide it up under the dash where it would be a total PITA to access. My problem was solved when I removed my half center console and found lots of space under there.
Cirkit Boss mounted to steel floor using included self-tapping screws:
I mounted the fuse block right in that spot, because it's underneath the removable rubber tray in the console... in the future, if I need to check fuses, I can remove the rubber tray without worrying about the rest of the console.
As mentioned, the fuse block has 4 switched 20A circuits. One circuit can power both front seat heaters. I cut out the included in-line fuses on the Rostra harness and saved them for use in the future. No need for them, since we are fused through the Cirkit Boss. So simply ran both Rostra hots to the #1 circuit on the Cirkit boss, and then ran the Rostra harness grounds to good clean metal under the dash.
I removed the center dash panel since it basically pops off once you have the console out. I ran the pink Switched 12V trigger wire from the Cirkit Boss to the hot wire in at the rear of the cigarette lighter (just used a T-connector).
While I had the center dash panel off, I decided it would look cool to mount the seat heater switches there... I think it turned out pretty well. Easy reach for both driver and passenger. One note, if you decide to mount where I did, you have to remove obstructing parts from the back of the dash when you drill... on the passenger side it's the little square cubby and on the driver side its the 4WD switch. They both come out easily with phillips screws from the back side.
Overall, happy with the process!