Has anyone upgraded the exhaust or turbo on their OM606 turbo?

I'd like more power. I know I can simply chip the ECU. More importantly though, I'd like better exhaust flow at high power. The application here is a G300DT, which is a g-wagen with the OM606.964 engine (from the factory). There are two problems with the factory setup.

1) At high altitude (8K+) the torque converter hooks up before the turbo produces any usable boost. The result is several seconds of turbo lag before any real acceleration happens. Low altitude performance is fine. A VNT turbo could make a huge difference in this behavior.

2) When loaded up for exploring the G tips the scales at over 7000lbs. I climb lots of long steep hills with all that weight. The "postal truck" aerodynamics also add to the drag. In the end, the engine is often driven flat out for 15-30 minutes at a time. Realistically, the exhaust system (stolen straight off the E300) was not designed for this kind of use. An equal length header tuned for ~2600RPM should flow much better than the convoluted log-style exhaust. A VNT turbo would also flow better at high loads than the KKK with it's tiny turbine wheel housing.

Well, that was long winded. Anyway if anyone has any suggestions, I'd appreciate hearing about them.

BTW: the OM606 puts up with this abuse very well. I did have to put a new head gasket into it at 170K miles, but that was largely due to a botched repair job performed much earlier in the vehicles life. Some idiot reused the stretch headbolts. Even so that job lasted 100K miles of abuse. About the only recurring issue is the crummy o-ring based fuel system.

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