So what does your logs of S60R or V70R say how much boost they do stock in first and second gear with TF80SC?
How much torque did you measured at wheel in gear one and two when you are on dyno and ecu requests 500 Nm with "tuned" ecu? How much torque was produced with stock tune? Did you notice any spikes?
How long did the TF80SC lastet forcing more than stock torque while driving it on a race track which repeatedly uses gear up and down shifts involving gear one and two? What gearbox oil temperature did you measured on that occasions?
How many different major and minor versions of TF80SC have been used in Volvo Cars from 2004 until today?
What are the differences of TF80SC from 2004 P2X and late 2014 P3X versions?
With how many different Volvos of that age have you worked in which different climate conditions to confirm your observations?
You don't know? You have no logs? You have no measurements? You have never been on dyno? You only drive your non R on your street nearby? No other Volvos?
Ok, then you might rethink who is writing bullshit here
Everyone calm down.
There are two reasons why you would want to limit torque in the 1st and 2nd gear. Wear/chance of breakage and the fact that you will only get wheel spin if you apply more torque than the tires will be able to transfer to the road.
The second one is easy to quantify for an end user. Most road tires don't allow for more than about 1G in acceleration/deceleration on the vehicle they are made for and manufacturers tend to choose tires in this range as first fitment. Getting more grip usually means that tires wear crazy fast and the regular customer is not going to be pleased with that. If you happen to have access to, or are a person writing these ECU calibrations, you would know that the purpose for these limiters by the OEMs is said to be to eliminate wheel spin primarily.
The first one is extremely hard to quantify, as Daniel no doubt tries to illustrate. How can you be sure that gear boxes don't shatter up inside? You do a bunch of math based on material science of the materials used in the design of the gear box. You choose the materials that are cheapest to use, but still are "good enough" for normal road use of the gear box. After that, you do a lot of testing, find out when the gears actually break under certain circumstances to make sure your theoretical calculations and design fit the application of the gear box.
There is a safety margin, it is both calculated and proven with testing in how strong these gears are by the time they are bolted to a mass production vehicle.
The fact that your gear box hasn't blown up yet is statistically irrelevant. Manufacturers would like the number of gear boxes that blow up to be 0, but 1 in 100.000 is totally acceptable. 1 in 10 obviously is not.
Until you test over 1000 gear boxes, or go through all the tests that Daniel describes with a dozen gear boxes or so, you should assume that these gears aren't designed to take much more load than the design of the road car calls for.
Volvo is known for putting in serious safety margins in their older designs. in the nineties they were forced to cut costs because of competition and once Ford took over, there was a lot more cost cutting to increase margins (make profit). These gear boxes are clearly commissioned in that era and we all know that there were many revisions to fix problems with reliability and durability.
TL;DR One or a few end users experiences mean nothing compared to the design and research data put in by Aisin and Volvo. Don't expect the box to be capable of handling more than 1G acceleration on stock tires because that would make it too expensive and outside of the scope the box is used for.
In practice, lifting the torque limit by a lot will only be beneficial for acceleration if you use extra sticky tires. Otherwise you will only generate tire smoke and possibly little bits of gear shattered inside your box.
