Product version displayed in WIX-made MSI file properties

For reference, here's a VBscript example that I'm using in my build process to grab such prior to creating a boostrapper.

Dim installer, database, view, result

Set installer = CreateObject("WindowsInstaller.Installer")
Set database = installer.OpenDatabase ("my.msi", 0)

Dim sumInfo  : Set sumInfo = installer.SummaryInformation("my.msi", 0)
sPackageCode =  sumInfo.Property(9) ' PID_REVNUMBER = 9, contains the package code.

WScript.Echo getproperty("ProductVersion")
WScript.Echo getproperty("ProductVersion")
WScript.Echo sPackageCode
WScript.Echo getproperty("ProductName")


Function getproperty(property)

    Set view = database.OpenView ("SELECT Value FROM Property WHERE Property='" & property & "'")
    view.Execute
    Set result = view.Fetch
    getproperty = result.StringData(1)

End Function 

So I did find a way of doing it without changing the version number.

I change the Product GUID with every build, but keep the Upgrade GUID the same.

I also had to change the RemoveExistingProducts to Before='InstallInitialize'. Otherwise it left only the 'deltas' between builds in the install path.

As noted by Wim below, I can replace the generated Product GUID with '*'.