Originally Posted by
Fredrikrosen
Is it enough to use the upgraded version of the 2003 belt?
There is a superceded belt for '03, I don't think it's considered the "upgrade" to '04-up, pulleys and belt. Not mandatory, it doesn't seem to be a time bomb or anything, but was upgraded by the factory in '04 for a reason.
Does not a XB9S -2003 have the Thunderstorm?
The Thunderstorm engine was put into all '08 and up XB's. It has the bigger crank pin and upgraded oil pump design. IMO the earlier engines are totally fine and take quite a bit of abuse. If it's worth it to you, get one. If not, no big.