I think getting the Ultra Racing- Rear sway bar shipped from Malaysia and installed for around $200 is a good deal. The rest of the 7 pieces they offer for around $120-$135. I emailed Mitsubishi about part numbers for the (stock) rear sway bar and the front upper strut brace. They told me to buy a third party rear sway bar or shock tower brace and have it installed. Since both use factory hardware to install they would not void the warranty. They did offer me a part number for the front top strut tower brace in the US, but told me that the rear sway bar was not available in the US because it is not shipped there or offered on any models even though it is offered in other markets. They even apologized for my conceived lack of performance of the model (2015 DE). Per their mail, "The Front Sway Bar Part Number is 4056A139".
-Chris