Well, this may not be a very popular thread or maybe it will be, but I've got to do it, to give some perspective that is lacking in the forums:
First, off, I'm 42, so if you are 24, my opinions may be of less value to you, as our perspectives may be different. I'm not telling you how to think. I'm just offerring a perspective. However, I don't live a sedentary life, so we may be more alike than you think. Every car I've owned since 1987, save a 1996 Taurus SHO that didn't come with one, has been a stick-shift, and I would consider myself a decent, but not great, backyard mechanic. I can handle a brake job, I did the suspension on my 2001 VW Passat, and have done a few timing belts when I was younger on a couple of Fords when the engine bay was bigger (sorry, I admit I paid for the timing belt on my '08 Passat). Anyway, enough background.
As my VW has 103,500 miles, today, I spent 12 hours today removing my intake manifold (for the first time), cleaning each port meticulously, replacing the oil, and changing the spark plugs.
Performance after the drive was exactly as it was before the modification. I tested the car in both the stock and chipped (93 octane) configurations and felt no difference. I realize that butt-dynos are not very accurate, but if you read the comments out there for this maintenance, a normal reader would expect the car would turn into a raped ape. Not in my case.
Yes, my ports were clogged with goo, and cylinders 2 and 4 (counting from the timing belt which was just replaced also this week, so no comments about a stretchy timing belt) were particularly gummed up on the valve stems.
I weighed each divider/tray before and after cleaning and found that I removed 1 gram of goo per port (the divider was 26 grams before in each case, 25 grams after in each case). Assuming the density is similar to plastic (not exact, but close), this means that the thickness of the goo on the divider was roughly 0.05 mm thick assuming 20 square centimeters of surface area on the trays (total for both sides). As a engineer, this was my first guess that the benefits wouldn't be huge.
So, I'm just sharing a perspective. If you are a curious person and enjoy tinkering and doing light-to-moderate maintenance, that you may wish to know that this isn't like a brake job or changing the cam follower. This job is a pain in the ass if you are on a time limit.
Thankfully, I put everything back together and the car ran fine but at a few points along the way, like when I couldn't get the intake off no matter how much effort (this was due the intake manifold support bracket bolt getting hung up during removal), I was literally just wanting to put my tools away and go back inside the house. However, I don't quit, so I just finished.
The build up on my engine, at 105,000 miles looks better than some cars I've seen. Is that because I have a lot of highway miles? I don't know. I'm smart enough to know that this maintenance on your car may make a significant difference in performance, but if I were to guess, it does not make a difference that matches the performance claims from some.
Take this for what it is worth.