diff --git a/SabreTools.DatFiles/DatHeader.cs b/SabreTools.DatFiles/DatHeader.cs
index 26783f3b..deaa3a12 100644
--- a/SabreTools.DatFiles/DatHeader.cs
+++ b/SabreTools.DatFiles/DatHeader.cs
@@ -507,18 +507,19 @@ namespace SabreTools.DatFiles
         /// <summary>
         /// Generate a proper outfile name based on a DAT and output directory
         /// </summary>
+        /// <param name="datHeader">DatHeader value to pull information from</param>
         /// <param name="outDir">Output directory</param>
         /// <param name="overwrite">True if we ignore existing files (default), false otherwise</param>
         /// <returns>Dictionary of output formats mapped to file names</returns>
-        public Dictionary<DatFormat, string> CreateOutFileNames(string outDir, bool overwrite = true)
+        public static Dictionary<DatFormat, string> CreateOutFileNames(DatHeader datHeader, string outDir, bool overwrite = true)
         {
             // Create the output dictionary
             Dictionary<DatFormat, string> outfileNames = [];
 
             // Get the filename to use
-            string? filename = string.IsNullOrEmpty(GetStringFieldValue(DatHeader.FileNameKey))
-                ? GetStringFieldValue(Models.Metadata.Header.DescriptionKey)
-                : GetStringFieldValue(DatHeader.FileNameKey);
+            string? filename = string.IsNullOrEmpty(datHeader.GetStringFieldValue(DatHeader.FileNameKey))
+                ? datHeader.GetStringFieldValue(Models.Metadata.Header.DescriptionKey)
+                : datHeader.GetStringFieldValue(DatHeader.FileNameKey);
 
             // Strip off the extension if it's a holdover from the DAT
             if (Utilities.HasValidDatExtension(filename))
@@ -529,7 +530,7 @@ namespace SabreTools.DatFiles
                 outDir += Path.DirectorySeparatorChar;
 
             // Get the current format types
-            DatFormat datFormat = GetFieldValue<DatFormat>(DatHeader.DatFormatKey);
+            DatFormat datFormat = datHeader.GetFieldValue<DatFormat>(DatHeader.DatFormatKey);
             List<DatFormat> usedFormats = SplitFormats(datFormat);
 
             // Get the extensions from the output type
diff --git a/SabreTools.DatTools/Writer.cs b/SabreTools.DatTools/Writer.cs
index 0a7b9139..ce7a284f 100644
--- a/SabreTools.DatTools/Writer.cs
+++ b/SabreTools.DatTools/Writer.cs
@@ -16,6 +16,76 @@ namespace SabreTools.DatTools
     /// </summary>
     public class Writer
     {
+        #region Private Constants
+
+        /// <summary>
+        /// Map of all formats to extensions, including "backup" extensions
+        /// </summary>
+        private static readonly Dictionary<DatFormat, string[]> ExtensionMappings = new()
+        {
+            // .csv
+            { DatFormat.CSV, new string[] { ".csv" } },
+
+            // .dat
+            { DatFormat.ClrMamePro, new string[] { ".dat" } },
+            { DatFormat.RomCenter, new string[] { ".dat", ".rc.dat" } },
+            { DatFormat.DOSCenter, new string[] { ".dat", ".dc.dat" } },
+
+            // .json
+            { DatFormat.SabreJSON, new string[] { ".json" } },
+
+            // .md2
+            { DatFormat.RedumpMD2, new string[] { ".md2" } },
+
+            // .md4
+            { DatFormat.RedumpMD4, new string[] { ".md4" } },
+
+            // .md5
+            { DatFormat.RedumpMD5, new string[] { ".md5" } },
+
+            // .sfv
+            { DatFormat.RedumpSFV, new string[] { ".sfv" } },
+
+            // .sha1
+            { DatFormat.RedumpSHA1, new string[] { ".sha1" } },
+
+            // .sha256
+            { DatFormat.RedumpSHA256, new string[] { ".sha256" } },
+
+            // .sha384
+            { DatFormat.RedumpSHA384, new string[] { ".sha384" } },
+
+            // .sha512
+            { DatFormat.RedumpSHA512, new string[] { ".sha512" } },
+
+            // .spamsum
+            { DatFormat.RedumpSpamSum, new string[] { ".spamsum" } },
+
+            // .ssv
+            { DatFormat.SSV, new string[] { ".ssv" } },
+
+            // .tsv
+            { DatFormat.TSV, new string[] { ".tsv" } },
+
+            // .txt
+            { DatFormat.AttractMode, new string[] { ".txt" } },
+            { DatFormat.Listrom, new string[] { ".txt", ".lr.txt" } },
+            { DatFormat.MissFile, new string[] { ".txt", ".miss.txt" } },
+            { DatFormat.EverdriveSMDB, new string[] { ".txt", ".smdb.txt" } },
+
+            // .xml
+            { DatFormat.Logiqx, new string[] { ".xml" } },
+            { DatFormat.LogiqxDeprecated, new string[] { ".xml", ".xml" } }, // Intentional duplicate
+            { DatFormat.SabreXML, new string[] { ".xml", ".sd.xml" } },
+            { DatFormat.SoftwareList, new string[] { ".xml", ".sl.xml" } },
+            { DatFormat.Listxml, new string[] { ".xml", ".mame.xml" } },
+            { DatFormat.OfflineList, new string[] { ".xml", ".ol.xml" } },
+            { DatFormat.OpenMSX, new string[] { ".xml", ".msx.xml" } },
+            { DatFormat.ArchiveDotOrg, new string[] { ".xml", ".ado.xml" } },
+        };
+
+        #endregion
+
         #region Logging
 
         /// <summary>
@@ -83,7 +153,7 @@ namespace SabreTools.DatTools
             _staticLogger.User($"A total of {datFile.DatStatistics.TotalCount - datFile.DatStatistics.RemovedCount} items will be written out to '{datFile.Header.GetStringFieldValue(DatHeader.FileNameKey)}'");
 
             // Get the outfile names
-            Dictionary<DatFormat, string> outfiles = datFile.Header.CreateOutFileNames(outDir!, overwrite);
+            Dictionary<DatFormat, string> outfiles = DatHeader.CreateOutFileNames(datFile.Header, outDir!, overwrite);
 
             try
             {
diff --git a/SabreTools.Test/DatFiles/DatHeaderTests.cs b/SabreTools.Test/DatFiles/DatHeaderTests.cs
index 7ba07346..87dc3d4b 100644
--- a/SabreTools.Test/DatFiles/DatHeaderTests.cs
+++ b/SabreTools.Test/DatFiles/DatHeaderTests.cs
@@ -20,7 +20,7 @@ namespace SabreTools.Test.DatFiles
 
             // Invoke the method
             string outDir = "C:\\Test";
-            var actual = datHeader.CreateOutFileNames(outDir, overwrite: true);
+            var actual = DatHeader.CreateOutFileNames(datHeader, outDir, overwrite: true);
 
             // Check the result
             string expected = $"{outDir}{System.IO.Path.DirectorySeparatorChar}test.{extension}";
@@ -38,7 +38,7 @@ namespace SabreTools.Test.DatFiles
 
             // Invoke the method
             string outDir = "C:\\Test";
-            var actual = datHeader.CreateOutFileNames(outDir, overwrite: true);
+            var actual = DatHeader.CreateOutFileNames(datHeader, outDir, overwrite: true);
 
             // Check the result
             Assert.Equal(28, actual.Count);