Project advice needed: ~500hp M103 or OM606?

[boostivison]

Hello folks,

I've been dreaming, planning and thinking of building a OM606 Superturbo but since I live in Germany it's very hard or next to impossible to get a car like that on the road legally. Also dieseltax is like 830€ per year while tax for a M103 3,0 is like 220€ per year.

It would be much easier to drive a w124 with a turbo'ed 3,0 M103 around here. I know a bit about the diesel build since it was my focus in the last months. I also already got a fine RS203 injection pump off a OM603NA.

Could you be so kind and tell me your opinions of the pros and cons of a M103 vs. a OM606 build? I was aiming for about 500hp in any case.

Of course, the cost is a very big factor as well
You can leave the costs for the Motor and the body out of this since surely you don't know the prices for these engines in Germany and I do not expect you to Let's just keep it easy and say that there's not a big difference in the prices. Meaning a complete car with a 3,0 M103 is not way more expensive than a complete car with a OM606.

But keep in mind that I'd like to put it all in a w124 chassis (which I don't have yet). So I guess it's an advantage on the M103 since I wouldn't have to buy a w124 and a w210 300td.

Thanks!