How to set different height for GroupHeaderTemplate and ItemTemplate?

I want to set variable height for my list both header as well as items in the list. I have set HasUnevenRows = true, but when I set a value for RowHeight that value sets the height for both GroupHeader as well as ItemTemplate, but I want them to be different. Can someone help me out?

My code looks something like this

    ListView  newList = new ListView
     {
            HasUnevenRows = true,
            //RowHeight = 60,

            GroupHeaderTemplate = new DataTemplate( ( ) =>
            {
                    // some UI code

                return new ViewCell 
                {
                        View = grid,
                };
            )},

            ItemTemplate = new DataTemplate( ( ) =>
            {
                    // some UI code
                    return new ViewCell
                {
                    View = grid;
                };
             }),
            GroupDisplayBinding = new Binding("Title"),
            IsGroupingEnabled = true,
            ItemsSource = SetupMainProcessList(),
    };