I've got an 89' 300D with the OM603 N/A engine. I have looked into turbocharging it but it seems like it may be more trouble than its worth, because I may be lacking the engine internals to support the turbo. I am looking to get some more power out of this thing. I understand its never going to be a 'fast' car by any means. That in mind, what options am I looking at to get some more power, and what have people modified on these engines?

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1984 300TD OM617 project. Rusted apart exhaust, leaking roof, bad interior. WIP
1983 300D OM617 straight piped, rusty, dented, and sketchy.
1982 300D OM617 parts car, assumed low/no compression at this point.
2005 F250 6.0L, custom tuned, stage 2 VGT, 175/30 injectors, all supporting mods. Currently parked with a smoked transmission.
Sold: 1989 grey market 300D OM603 N/A