You don’t need to change the booktype if you have a relatively recent PS2, see below;
PS2 DVDR/RW support revisions:
Version 1-3 DVD-R/RW only
Version 4 DVD-R/RW & DVD+R
Version 5-10 DVD-R/RW & DVD+R/RW
If your not sure you can check here what revision yours is at the link below.
Version 9 & 10 are the most common PS2’s around and it will play either - or + format discs just fine.
(With the exception of the new DVD+R DL [double layer] discs I’ve heard others got these to work fine in their PS2 but the test movies I made using Ritek & Verbatim discs refused to play properly in my v9 PS2 and two other v9’s I tested them in but played fine in normal DVD players, changing the booktype made no difference.)