If you have ever had the desire of changing that "3G" indicator on your iPhone 4 to "4G" or "LTE," or maybe you have an iPhone 4s and want "4G" to say "LTE," then there's a new free jailbreak tweak called KDLTE4G for iOS7
by iOS developer Sean Young that will let you do just that.
The tweak isn't limited to the iPhone 4 and iPhone 4s, of course, but what the tweak lets you do is change the cellular data indicator to 4G, LTE, or back to the default indicator whenever you want to.
The tweak adds a preferences pane to the Settings application where you can configure the cellular data indicator that you want to display in the Status Bar:
When you select the "Default" option, your Status Bar's cellular data indicator will show the usual icon for whatever network you're on. For example if you're connected to a 3G network, then the 3G indicator will display. If you're connected to a 4G network, then the 4G indicator will display.
When you select either the "4G" or the "LTE" option from this list, that is the indicator that will always show no matter what. So you might be connected to a 3G network, and a 4G indicator might show (if you picked it), or the LTE indicator might show (if you picked it). The changes you make here don't apply immediately, and you don't have to respring your device. Just wait about 5-8 seconds after making a change, and your changed cellular data indicator will appear in the Status Bar.
Obviously, this tweak doesn't give your dated iPhone 4 any 4G or LTE capabilities; this tweak is only intended to spoof your cellular data indicator to make it look to the eyes that you're connected to a 4G or LTE network. It's merely aesthetic, and a nice way to customize your iOS device.
While the customization is nice, it's also going to make it difficult for you to actually know what kind of network you're on. Your cellular connection could drop from 3G to E, and yet if you have "LTE" selected in the preferences pane, your Status Bar is still going to say "LTE," so you won't actually know that you're on a slower Internet connection until you start noticing the ultra-slow speeds, or you return to the "Default" option to see what radio you're using.
If you want to give KDLTE4G for iOS7 a try, it's available for free right now in Cydia's BigBoss repository.
KDLTE4G for iOS7
Cellular iOS device
iPhone 4 running iOS 7.0.4