Hi,
I have a PS2 with the MESSIAH 2 mod chip installed on it and i tried to backup a dvd game and burn it onto a DVD-R disc it doesnt play.
PS2 MODEL - SCPH-30003
MOD-CHIP - MESSIAH 2
DVD-RW - MSI DVD RW +R -R DUAL LAYER
DVD MEDIA - datewrite-r (4x) & goallover dvd-r(x)
SOFTWARE - DVD Decrypter, NERO
on all software i try to burn at 1x and it doesnt allow me or it starts at one and then begins to make its way to 4x.
PS2s and Videogame consoles in general are very picky about what they read. You can’t just throw any peice of junk at them at expect them to work. I would give Ritek/Ridata (official brand if possible as there are some cheap quality knock-offs) DVD-R a shot. If Ritek don’t work for you then try some Taiyo Yuden DVD-R (if you can find them) and if not then Verbatims made in Singapour wouldn’t be a bad choice. Datawrite are well known to be all over the place with quality and goallover? No idea but it sure sounds like cheap media to me. 
my experience is that you need really good (high quality) burns for a good result on older ps2 versions like yours.
the burnspeed is not the problem: lower speed does not mean better burn.
my mostly used medias are ritek 4x dvd-r (ritekg04) and TY