pdf quality poor - mac

the quality of the pdf's i create are poor.  

I tried the export option, but there is no way to select the print style that I use.

I set all up as if to print to a local printer (my HP 430 plotter) used my plotstyle and then clicked the 

pdf option at bottom left of dialog.  PDF was created , but lineweights are not what they should be.

 

Ideas??

DS v1R2.1 mac

macbookpro OSX 10.7.4