I would not bother balancing a new set unless it's horribly out of spec, because if you're reusing the same shims that previously led to a balanced set, there's a good chance the new set will end up balanced as well once the nozzles break in. Of course testing the injectors before installation is always a good idea, but it's not absolutely necessary. If the engine runs smooth and sounds good, it's unlikely there's anything wrong with the injectors.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL