Pedro,
You are correct. Your Technobrace is not just a bar with two holes on the end. There are also two flats.
I don't question that it will work. Until recently I had a 1" diameter solid aluminum bar with two holes on the ends and flats on my car since August. I measured perfectly. I drilled perfectly. It didn't fit the first time. I measured again, I drilled again, still had trouble fitting. After quite a bit of screwing around I eventually got it to fit. That's just the way this kind of thing goes.
The problem is that no matter how perfectly you measure it and drill it for your car there is no assurance that it will be perfect for my car. I can't imagine there's a huge amount of difference between cars here, but it wouldn't take much to make fit a real issue. Just 3 mm difference between the 986 and 987 means you offer two different size bars. Is that really a difference in the structure between those models or a difference between the individual cars you measured? How many cars did you measure to get your perfect numbers? What about the S? What about the Cayman? I'm not trying to be nasty, just making a point.
That's why I moved to an adjustable bar with adjustable heim joints. It'll fit any car and is more of a universal solution. I also feel a bit better about having something that's made for racing and rated for 7,000+ lbs tensile (aluminum heavy duty heim joints) and 9,000+ lbs tensile (steel heavy duty heim joints).
Ultimately people will chose what "fits" best for them.
And either way at least folks now have MUCH lower cost options to the Mantis bar.