Currently, all "tuning modules" for Bosch Smart engines are pointless. Not only are they expensive, but they are also generally unreliable – sooner or later, the Bosch system detects the module and reports an error.
Why are these modules pointless? Because for a few dozen euros (currently €35 – competition does its job, which is a very reasonable price for the service), you can upload software that increases the maximum speed limit from 25 to 32 km/h. In addition, the maximum assistance speed is fully configurable in the Bosch Flow app. You can set the legal limit of 25 km/h on-road and use the increased maximum speed in off-road mode. Simply move the speed limit slider in the Flow app.
For those who need a theoretical lack of limit, simply combine the US limit (32 km/h) with a reduction by half (or less, but half will give a simple estimate of the current speed) of the possible wheel circumference setting. Why theoretical? Because reaching 64 km/h is only possible for road/gravel bikes with the right gear ratio. In addition, maintaining a speed of >50 km/h requires a lot of power, and although the motor can provide 0.6 - 0.75 kW of power, it can only do so for a relatively short time. Even on a motor with a 25 km/h limit, this can be felt on long, steep climbs. Motors designed for bicycles with a speed limit of 45 km/h have a slightly different design than motors with a lower speed limit. Therefore, the CX motor cannot simply be reprogrammed to a 45 km/h model. Can the CX handle a constant speed of 45 km/h? Perhaps. Does it make sense to increase the limit to 64 km/h? For some, yes, if the 25/32 km/h limit is too low for them. The fact is, they should switch from a bicycle to a moped (even an electric one) if they want to travel at such speeds on public roads. Alternatively, they could switch to approved bicycles with a 45 km/h limit (registration, insurance, etc.). That's the law.
Leaving aside the debate about maximum speeds, hardware limiters do nothing more than programmatically set the limit to 32 km/h and reduce the wheel circumference. What's more, they do it worse, because they are much more prone to error. And they cost a lot. Much more than the software speed adjustment service. This makes software speed increase using BDT3 unrivalled. At least until Bosch introduces regional restrictions, i.e. removes the possibility of reprogramming in areas where 25 km/h applies (e.g. EU/UK) to the limit applicable in the USA, for example. This means that a service technician from the EU will not be authorised to activate the 32 km/h limit. This is easy to implement. Similarly, it is possible to block a wheel circumference that is too small. However, for now, there are no such restrictions, hence the possibility of reprogramming the maximum speed limits of Bosch motors to speeds higher than those permitted in a given area. Is this legal? No. Just like "tuning modules", but people will use it anyway. In the case of software, it is even easier to set a legal assistance speed range of up to 25 km/h than with some modules. In addition, the installation of modules can be problematic, especially with magnets on the wheel rim.
Hence the conclusion that tuning modules are currently pointless. After reprogramming, the only noticeable changes are: a message about the need to be careful and switching to off mode (probably required by law in the US). Can anyone find fault with this? In the case of standard factory bikes, it is highly unlikely. Especially if there is a 25 km/h speed limit on public roads. Of course, if the limit is removed (the so-called 64 km/h), such a bicycle travelling on a public road can quickly be classified as not complying with legal standards, with all the consequences that entails, such as driving a vehicle without a licence (no type approval), no driving licence, no insurance... Personally, I would not take the risk. Riding off public roads does not, of course, have these restrictions, but even here it is worth exercising restraint, if only for your own safety...