I don't think the K5006-Z is available in the UK yet, so I'm guesing that you're from somewhere that isn't the UK.
Speed with mboile devices is a very variable thing. The main factor that affects speed is the bearer; 2G, 3G or 4G - 4G being the fastest. Bear in mind you need to have a $g capable device, and maybe tariff as well to be able to use 4G. To find out, for sure, which bearer covers your location, you'd need to speak to the mobile network operator for the country you're using it in as the forum staff here are all Vodafone UK employees, so can only really provide information on UK based coverage.
Once you've worked out the bearer and the capabilities of your K5006-Z, this should give you an idea of approximate speed. Bear in mind that packet data access is s shared resurce amongst the mobile users connected to the same site as you. If you don't get the speed you've been expecting it's highly likely that it's because there are a lot of subscribers using the same mast as you.
As a general rule of thumb, the network will serve you the best speed it can.
I appreciate that doesn't really answer your question, but to get an answer that's useful you'd really need to ask the people that operate the network you're using and what I've mentioned above is the reason why.
