After the recent claim that three out of four major carriers in the U.S. throttle iPhone and iPad data speeds the folks over at AnandTech decided to further investigate the issue. They ended up determining that the original assertion, which has been deleted, is untrue. AnandTech mentioned the following regarding the matter:
Apple doesn't limit cellular data throughput on its devices ó there's both no incentive for them to do so, and any traffic management is better off done in the packet core of the respective network operator rather than on devices. Sideloading tweaked carrier bundles isn't going to magically increase throughput, either.
Again, there's no reason for Apple to want to arbitrarily limit their devices, and the reality is that they don't, at all, on any version of iPad or iPhone or in any of the carrier bundles they've distributed for network operators. If anything, Apple has long been one of the few handset vendors who initially understood the importance of limiting annoying operator customizations. The Carrier Bundles are quite literally the only place in the entire OS they have indirect access (through Apple) to toggles they can play with.