modify UPX

Yesterday I was modify a UPX file,Fi Detected it is UPX + cryptor (��PE),PEID use Normal scan and Deep scan Detected it is Win32 PE File - GUI,use Hardcore scan Detected it is UPX 0.89.6 - 1.02 / 1.05 - 1.22 (Delphi) stub -> Markus & Lazlo,pe-scan Detected it is neolite 1.0x

Now I have a question,how can I modify it let it can't Detected by FI and PEID?

those tool Detected what signature to sure it is a packed by UPX's File?

Thanks.