It's going to be hard to come up with a front undertray for our cars that will work for everybody, IMO. Wastegate dumps, downpipe size, oil filter location, intercoolers hanging down and their bracketry, etc. all need to be taken into consideration. Not to mention how low everything sits under there already, an undertray will be pretty close to the ground if trying to clear a 3" downpipe or something similar.
I've sat under my car and looked at it wondering if one could be built. It's doable, but looks like a pain in the ass due to the reasons I mentioned.