My B9 S4 motor mount DIY writeup (that should also apply to B9 S5, RS4, RS5):
After doing this yesterday with the help of some videos (thanks Need4built) and combining some guides from 034, I wanted to make a more complete DIY for people wanting detailed instructions without removing the whole front off the car, alternator, and AC compressor. I unfortunately did not take photos, but the guides from 034 have better photos anyways. I did this in my little 1 car garage with 2 floor jacks and 2 jack stands. I had a friend help, but you could do this on your own. Below are the tools required and writeup:
Guides:
Dropping the subframe: https://www.034motorsport.com/.../034motorsport-track...
Motor mount install: https://www.034motorsport.com/.../034-509-5041_Install...
https://www.youtube.com/watch?v=EGwE80eQTbI
Torque specs are all in the PDFs
Tools:
Engine support brace (I used the Pittsburg brand from Harbor Freight)
M10 triple square that can be turned with a ratcheting wrench (https://www.amazon.com/dp/B0D1Z46PRG...)
M12/M14 triple squares
Pole jack/floor jack that goes reasonably high. I have a floor jack for SUVs that was perfect.
T25/T30 bits
Torque wrench
Zip ties
Sockets, extensions, breaker bar, usual working on car stuff
Guide:
*You will need an alignment after doing this*
Jack up the front of the vehicle as high as you can while still being able to work in the engine bay. Obviously use jack stands. I jacked the car up from the back of the subframe with the 2 slanted bolts and put jack stands under the pinch welds.
Remove the wheels.
Remove the engine and transmission skid plates.
Remove the engine cover and heat shield.
Remove hood latch and radiator support plastic cover so you can take off the duct from the front bumper.
Remove the airbox/intake. (I have a 034 catch can and removed this as well)
Disconnect the battery
Install the engine support brace on the rear 2 mounting points on the top of the engine. Tension it just so the arms from the brace stay in place.
Remove the fender liners from both side and the plastic brace that's under the brake lines. You will need a 10mm and T25s.
Remove the front outer skid plate/lower fender liner plastic pieces.
Remove the 10mm bolts from the heat shielding attached to the subframe.
Remove the 4 M14 triple square bolts from the subframe. Place a pole jack or floor jack with a piece of wood under this part of the subframe and lift it so there is light pressure. This will be right under the steering rack.
Remove the 4 18mm bolts from the front portion of the subframe.
Remove the 2 13mm bolts from the front of the subframe.
Remove the 2 M12 triple square bolts from above the rear lower control arms.
Loosen and 1/2 way unthread the 4 rear 18mm subframe bolts.
Look at the steering rack and you will see a wiring loom attached to it. This will be intertwined with some other wiring looms. Disconnect the ground bolt and 2 electrical connectors from the top of the wheel well/under the air box so the wires are loose. These will prevent you from lowering the subframe and you do not want to break them.
Route the wires so they are separated from the rest of the wires. You will pull them through to the front of the car once you start to lower the subframe.
Slowly lower the subframe until you can fit the wires through the front of the subframe. There are some zip ties you will need to cut and other wires you will need to move out of the way. There is also a peg holding the loom into the steering rack. As you lower the subframe, you'll be able to separate them.
At this point you should be able to see the M14 triple squares through the wheel well holding the engine to the mount. Loosen and remove this bolt from the mount. If you cannot get access to it, slightly lower the engine. Repeat for the other side.
Once these bolts are removed, lift the engine an inch or 2. You will here it pop out of the mounts. Make sure to go only a few turns per side so it comes up evenly.
Remove the 2 13mm bolts from both sides of the motor mounts.
Remove the 2 13mm bolts on either side of the sway bar bushings and pull the sway bar down. (now is a great time to replace the front sway bar if you have one).
start to lower the subframe. I lowered it all the way and the floor jack was no longer supporting it.
Unplug the passenger side motor mount electrical connector.
Use a ratcheting wrench and the M10 triple square to remove the last bolt on the inner side of the motor mount.
There are 2 18mm bolts on the upper subframe that screw into the frame rail. Remove these bolts completely so the upper subframe is free to move around.
You should be able to wiggle out the passenger side motor mount. Lift the engine more if needed.
Install the new motor mount into place. Thread the 2 18mm bolts you took out back into place but leave them mostly unscrewed so you have more room to work.
Install the M10 triple square bolt into the inner side of the motor mount but do not tighten it down.
Install the 13mm bolts into the side of the motor mount and torque them.
Screw the 18mm bolts most of the way into the subframe. Leave room to tighten the M10 triple square bolt. There's not really a way to get a torque wrench in there so get it as close are you can. Plug the electrical connectors back into the mount.
Screw the 18mm bolts all the way back up but do not tighten them yet. You will want these loose when reinstalling the subframe or it will be hard to line up.
Repeat steps 25-33 for the driver's side mount.
Lower the engine onto the mounts. Make sure not to release tension on the engine since not everything is tight yet. It should line up with the holes easily.
Install the M14 triple square onto both sides of the engine mount. If the frame rail is in the way, loosen the 18mm bolts a bit and lower the engine more until you can get them in. Torque to spec.
If you needed to lower the upper subframe for that step, raise it again until it is just moveable. Raise the engine with it.
Start to raise the subframe, sway bar, and steering rack. There is a delicate balance of lining up the wiring loom and sway bar. Raise and lower the subframe as needed to get the loom installed back over the steering rack and routed back into place. Reinstall the zip ties that you cut.
Loosely install the sway bar bushings. These will need to be torqued at ride height.
Lift the subframe most of the way up and start installing the 13mm, 18mm, M12, and M14 triple square bolts while there is some wiggle room. This took some finagling, raising and lowering the subframe, and loosening and tightening most of the subframe bolts. Have some patience with this step and you'll get all the bolts back in.
Hand tighten all the bolts, reconnect the ground strap and 2 electrical connectors in the upper wheel well.
Install the intake back into the car (and anything else you removed like a catch can).
Reconnect the battery and start the car to ensure there are no error codes before you torque the subframe bolts. Once these are torqued, you won't want to undo them again so better to find any issues now if there are any.
Assuming all is good, torque the subframe bolts (all specs are in the sway bar install guide). The 18mm bolts into the upper sub frame should be the same spec as the 18mm bolts on the lower subframe which is 90nm +90 degrees. Use a sharpie or paint pen to keep track since there are a lot of bolts.
Reinstall the 10mm bolts into the heat shield attached to the subframe.
Double check all the motor mount bolts are torqued.
Reinstall the side skid plate/lower fender liner piece.
Reinstall the fender liners and plastic bracket. Install the 10mm plastic nuts and T25 screws. I'd wear a mask and safety glasses for this unless you like having tons of dirt in your eyes and mouth.
Double check the subframe bolts are all torqued.
Use floor jacks to lift the suspension to ride height and torque the sway bar bushing bolts.
Reinstall the skid plates.
Remove the engine support brace.
Reinstall the hood latch and engine cover.
Drive your car and listen for anything that sounds off. My mounts had increased vibration for a few hours and then got much better.
Feel free to message me with questions. I am by no means a mechanic and am obviously not responsible for anything you do to your car.