Well I've went into the res folder to spruce up an app icon figuring it would look much better with the modified alternative.
The icon png 's are stored in about five different folders.
In each folder there are mainly 3 icon files as png's
Of different sizes \large_icon.png being the largest I assume this would be the main app folder icon that displays as the package installer and home screen icon.
I've made changes to the icon that is being used to replace the current one's by copying them over and replacing them with the same file name for each.
The icon being used is the same for each, Around 57kb.
After successfully replacing the icons, rezipping the package and changing the
.apk the app shows up with the changed icon and will install but when the install is completed a notification comes up saying not installed.