The DMF was put on the 90 to protect the gearbox not the engine
The extra torque that is delivered at very low revs on the TDI 90 due to the VVT turbo would put the transmission at risk if you where repeatedly to rev it and drop the clutch very abruptly (boy racer ish)
A remapped 75 will not develope the same torque as low down, but some degree of care should still be used when setting off from a stand still to respect the gearbox
This is what I was going to say. The VGT turbo that's fitted to the TDI90 means that the engine can generate a lot of torque at low revs. Piston engines don't turn smoothly like electric motors, but instead create rotation with a series of 'kicks'. These kicks blend into a smoother, more continuous rotational force at higher revs, but at low revs the individual kicks are much more discernible. Without the DMF, the teeth inside the gearbox of a TDI90 would feel that they were being repeatedly hit with a very powerful hammer. The DMF absorbs these kicks and transmits a more continuous rotational force to the gearbox. The TDI75 doesn't require a DMF, even when remapped, because it's not able to generate big power/torque until it's spinning at higher revs.
My A2 was remapped 10 years and 120,000 miles ago. It just works flawlessly.
The A2 was designed to be an economical car. That doesn't just mean fuel efficiency, but also cheap road tax and cheap insurance. Rather than thinking of the TDI75 as a 75bhp engine that can be tuned to 100bhp, think of it as a 100bhp engine that's been restricted to 75bhp through software in order to keep performance, and therefore insurance, down. In this particular case, remapping the engine is simply removing its shackles, not squeezing every last drop out of it.
I've little doubt that, if I used the maximum power and torque that my engine produces at almost every opportunity, I'd reduce its life, but that's obviously not the case. A vast majority of the time, I pootle about in it, rarely asking it to accelerate in anger. Am I worried that its remap is inherently life-limiting? Not at all.
Cheers,
Tom