My 97 e300 is non turbo. Is there an after market turbo available for it? Better ones than stock? I hear the stock turbo isn't much improvement.

 

I do not know if it is the same on the New Diesels but on the Older ones the Turbocharged Engine while on the surface seems similar is not the same Engine as the non-turbocharged Engine. There is a lot of internal differances as to the cooling of the Pistons and parts were made stronger.
Also the Fuel Injection Pump (Calibration and internal parts) and the Smog Equipment would also be different as well as the Intake and Exhaust Manifold/pipe connections.
I guessing the same would apply to your Engine.

If it was just a simple bolt the Turbo on issue I am sure someone on eBay would be selling kits.