The pads are definitely large enough to heat you quickly.  The low setting is very warm, and the high setting is too hot.  They get to max temp about as quickly as factory heated seats.As the product states, it is for professional installation only, but it's really not that difficult.  Do a Google search for the product, and you'll find an installation guide.  The electrical part is the easiest.  They give you a fuse tab, so there's really not much electrical work required.Installation (done on a 2006 Mazda 3):Disconnect the bolts (probably 4) holding the seat to the car.Disconnect the battery ground!!!  Your battery will probably die from being unplugged so long, so be prepared to jump the vehicle.  Don't connect the battery ground until everything (mainly the airbag wires) are reconnected.Unplug any connectors(power seats, airbags...) from the seat.Remove the seat, and take it indoors.Start removing clips/clasps/velcro holding the seat fabric on (this is the most time consuming part).  It's very similar to doing upholstery on a couch.  The seats have metal clips, similar to staples.  This is what the included tool is for.  The tool did break within 10 seconds of me using it, but a normal pair of needle nose pliers works just as well.Only remove the clips that are necessary for placing the pads.  You don't really need to replace them if the fabric holds tightly by itself.Make sure you figure out where you want the pads before you uncover the sticky tape.Place the pads so that the wires are going toward the bottom rear of the seat.  Place sticky side onto the foam.  You may have to rip out a little hole in the foam for heating pad connectors to rest in.  This will prevent lumps in the seat.Ensure that the pad wires are in a good spot and won't get in the way of people sitting behind the seat.  You want them exiting the bottom rear of the seat.  You can always make an extra hole for the wires.Pull tight and make sure it looks and feels good before reattaching the fabric.  You don't want lumps or wrinkles.Re-install the seat.  Make sure wires will fit (along with your button location) to the fuse box.  Plug back in anything that was disconnected from the seats (airbags and other wires).Decide where to put the button.  I chose near my right knee.  This will allow you to drill the hole without removing any dash components.  Pick a location where you can drill without hurting anything, and still be able to run the wires from the hole.Run the wires from the rear of the seat to the foot well.  Depending on the vehicle, this can probably be done by shoving the wires between the carpet and the plastic trim.  I didn't have to remove any trim.Connect all the connectors so your're ready to install the fuse tab.Using your vehicle manual, choose a fuse.  You're car might have a &#34;heated seats&#34; fuse already allocated.  Make sure the fuse will turn off when the engine is off, and has the correct (or greater) amps.  I chose a ground location on one of the bolts in the pedal assembly in the driver's foot well.Your battery is probably dead by this point, so make sure everything is plugged in and in place, and reconnect the battery ground and try to start.  Jump the battery if needed.Make sure the switch works, and turns off when the engine is off.Put everything back together, hide wires with zip ties, and make it look good.