I know this has nothing to do with removing weight but I had the thought that reducing frictional loss wherever applicable could result in a similar quest.
Things like engine blueprinting ensuring everything is as close to equal as possible, looser clearances and windage, looser brakes, small diff yoke, rollerized transmission parts, etc. Basically stock eliminator type stuff. Some of these ideas might not be real practical on the street but for race-only cars they would be a worthwhile endeavor.
It might be obvious to most here but regardless, I think its born of the same mindset, trying to make a car quicker by looking in places that you normally would not. Like weight reduction, its also an age-old idea and not really OOTB so much but it is one that could use some more exploration. Might be cool to see some of those ideas presented as a whole.
