Do you have adjustable gears? If not, then yes you'll have to redo the timing. Have the crank and oil sprocket and intake cam timing marks line up. Ziptie the belt to the intake. Using the timing tool, compress the tensioner and put the pin in. Remove the belt from the exhaust cam, realign the marks and put the belt back on.
Grace: 1998 GST
Sera: 1998 XJ