PDFSaveOptions - can't control file size

Question

I am trying to automate the saving of all my layers as PDFs.  Yet, I am getting different results when I try to automate the saving process.  For example, I can save a file manually using "SaveAs..." in the menu, then setting my options using the tabs on the save as pdf window.  However, when I try to use the same settings in my code, it saves fine, but the file size is about 4 times te result of doing it manually.  I can set the "presetFile" for the SaveAs to use, but it causes the automatic process to stop and wait for input from me...which is the exact opposite of what one would want in an automation scenario.
Below are the save options I am using.  I have tried several different PDFEncoding types.  I've tried different downSample values.  I've tried different jpegQuality settings.  I've tried just about every combination of settings.  Nothing works!  I can never achieve the file size that I get from the same exact settings on the manual screen.  I am trying to just get my files to somewhere between 4 and 6 MB, but they keep ending up over 120MB.  No change I make has any real effect.
What am I doing wrong?
saveOpts = new PDFSaveOptions()
saveOpts.PDFCompatibility = PDFCompatibility.PDF16;
saveOpts.colorConversion = false;
saveOpts.destinationProfile = "U.S. Web Coated (SWOP) v2";
saveOpts.embedColorProfile = false;
saveOpts.optimizeForWeb = true;
saveOpts.profileInclusionPolicy = false;
saveOpts.encoding = PDFEncoding.PDFZIP;
saveOpts.downSample = PDFResample.PDFBICUBIC;
saveOpts.PDFStandard = PDFStandard.PDFX32003;
saveOpts.downSampleSize = 200;
saveOpts.downSampleSizeLimit = 250;
saveOpts.layers = false;
saveOpts.jpegQuality = 0;
var Panels = app.activeDocument;
Panels.saveAs(PDF, saveOpts, true,Extension.LOWERCASE)

Answer 1

I had trouble with the PDFSaveOptions too so I use scriptlistner.
function saveCopyAsPDF( file ) {
    var desc = new ActionDescriptor();
        var presetDesc = new ActionDescriptor();
        presetDesc.putString( stringIDToTypeID('pdfPresetFilename'), "Smallest File Size" );
        presetDesc.putInteger( stringIDToTypeID('pdfCompressionType'), 10 );
    desc.putObject( charIDToTypeID('As  '), charIDToTypeID('PhtP'), presetDesc );
    desc.putPath( charIDToTypeID('In  '), file );
    desc.putBoolean( charIDToTypeID('Cpy '), true );
    desc.putBoolean( charIDToTypeID('Lyrs'), false );
    executeAction( charIDToTypeID('save'), desc, DialogModes.NO );
saveCopyAsPDF( new File('~/Desktop/test.pdf'));