My 1991 300D, with 167K runs great, but it is just a tad noisy. I tried diesel purge and that did quiet it down some, but I was thinking about just replacing the original injectors for good measure. My mechanic mentioned that there is a local Bosch shop that will exchange my injectors for rebuilt injectors at a very small cost. What is the scoop on new vs. rebuilt? At 165K if the car is running good is it just a waste of my time/money or should I go for it?