Is tuning a car a good or bad thing?

Looking for something unique and personal in today's world is for many a requirement when purchasing a new car or looking into modifying an existing one. There are plenty of companies offering everything from engine tune-up to purely cosmetic enhancements to total transformations. Some are better than others and while some are on the total opposite end of the scale, they all offer some kind of modification. Something unique to you.

I'm pretty sure that most, that look into any kind of modification of their car, have all read the horror stories and the praise for almost every company offering what one is looking for. Everything from "stay far away from this company" to "my car is faster and grips the road like never before" to "fuel economy down the drain, but it looks good".

Surely there are many more examples, more than those mentioned, but the question that lingers in the back of the head is if a spoiler kit with side skirts actually enhances the performance of the car. How it travels down the road and especially how the wind funnels its way around the car at speed, does it really make a difference?

If you take a car like a Ferrari, Lamborghini, or McLaren and then you put on a wing at the back and maybe change the rims to a size bigger and for good measure, you change the splitter at the front and maybe also add some side skirts, while you are at it. I seriously doubt that a modification like that would have a positive impact on how a Ferrari, Lamborghini, or McLaren handles at high speed or when cornering since those kinds of cars is already finely tuned weapons. The overall effect, I think, would be more of a negative one, since I highly doubt that the engineers at Ferrari, Lamborghini, or McLaren don't know anything about aerodynamics or fluid dynamics. It's not like it's their first time dealing with such things.

As an example, Ferrari released their F12 TDF this year and in their press release, they stated that the F12 TDF had a "Significant increase in downforce, +87%, which has reached unprecedented levels for a front-engined V12 Berlinetta.", which would mean that they know what they are doing. The same goes for Mclaren who mentioned in their press release that the "The 675LT produces 40 percent more downforce than the 650S", which also would make sense since both Ferrari and Mclaren are involved in the F1 circus and that would make them by default, really good at aerodynamics.

Yet, there are tuning companies that offer body kits for both Ferrari and McLaren cars, as well as Lamborghini and a ton of other cars, manufacturers like Porsche, Mercedes, BMW, Maserati, Aston Martin, Nissan, etc., etc. Some claim that they are able to increase downforce, and some mention nothing of such, but the big question is, would a body kit on a Ferrari, Lamborghini, or McLaren actually make the car better? Would it, really, improve car handling and efficiency?

Give the fact that you are actually modifying something that has been tested, developed, and refined from its inception to release in such a way that it's creating a perfect balance between handling characteristics, efficiency, and outright top speed. What testing, development, and refinement is taking place at a tuner company that could radically improve an already improved product? or is it more like putting stripes on your car to make it go faster?

Nissan is one automaker that spent a considerable amount of time tuning, refining, and developing the new Nissan GT-R (R35) to reach the perfection that it wanted for its release back in 2007 at the Tokyo Motor Show. Nissan has in many documentaries and videos talked about the sophisticated drive train as well as the aerodynamics at play, yet today it's one of the more popular cars to modify, just like the previous generation of GT-Rs, but are we really making some good better or are we actually ruining the original?

Looking at it from a distance makes me wonder if our obsession with modification actually is undoing most of what the engineers at these companies have mastered and perfected over a long period of time. That is the question, a valid question that begs to be answered.