You can't increase the speed of these devices. It all depends on the signal reception and the limits of the pre-paid SIM card or your contract. Even if you apply the "network tweaks", the speed will be the same. Of course, it will increase just a little through ports opening, TCP pipe, HTTP boost, etc. but it isn't worth the effort. However, you can use applications like TuneUP Utilities to tweak the network settings.