Depends if you want to keep within the manufactures rating for the gearbox. To find that out you need to search for the transmission type. And then search for the spec for that.
You'll find if you want a performance EV you'll need to use the gearbox from a performance ICE.
For example a BMW E46. The gearbox in a 330i rated for 320 NM, the gearbox in the 325 is 250 NM.
400 ft-lb is 540 NM - look into a getting a racing tranny? The Audi 1.8T is probably around 200 NM.
Then you also need to upgrade brakes, suspension etc.
Also have a look at what tuners have done. Here is an example: