Me refería a otras opciones del método Output()
Cita: Output
string Output([string name, string dest])
Description
Send the document to a given destination: browser, file or string. In the case of browser, the plug-in may be used (if present) or a download ("Save as" dialog box) may be forced.
The method first calls Close() if necessary to terminate the document.
Parameters
name
The name of the file. If not specified, the document will be sent to the browser (destination I) with the name doc.pdf.
dest
Destination where to send the document. It can take one of the following values:
* I: send the file inline to the browser. The plug-in is used if available. The name given by name is used when one selects the "Save as" option on the link generating the PDF.
* D: send to the browser and force a file download with the name given by name.
* F: save to a local file with the name given by name (may include a path).
* S: return the document as a string. name is ignored.
See also
Close().
Pero supuse que ya lo habías visto.
Sitio oficial de FPDF
http://www.fpdf.org/
Te invito a consultar la referencia de todo lo que uses, de veras.