Couple things:

Currently working on a '92 300D 2.5, with an OM602. Been looking at replacing DV seals and springs, and maybe the lift pump, but I figured I might as well price a replacement pump with upgraded nozzles for comparison - turns out it's not too much, but it of course leads to more questions.

I'm looking at upgrading my stock 5,5mm elements to 6,0mm. It's not a huge difference, only about 10%, but I'll be happy if it translates to a 10% performance increase. I'm basically looking for the reliability of a fresh pump and any upgrade will be a bonus. But will this work with a stock engine? I don't want to get into installing an intercooler, monitoring EGTs, or replacing the clutch or transmission.

My second question is about the turbo - should I upgrade, or do I have to? I'm looking at rebuilding my T25, and have the option of converting to T28 components. I don't really know what the difference is. I gather my max boost won't change, since I'll be converting to a pressure-activated wastegate, and anything over 15PSI or so will be wasted. But will it spool up faster or otherwise perform better than the T25 at equal boost pressures?

Thanks for any opinions/advice.

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