Depends on how you balance cost, risk of breakdown, and hassle of intermediate maintenence intervals. Some would say you don't even need to do the timing belt at 90k. Mr. T says the belt should be done. Extra 'while you're in there' items determined by how you weigh the factors above. Do consider this is a group of enthusiasts with many over-maintaining their rigs. I'm in that camp.Is it necessary to do all these at 90k?