The car is not yet in drivable condition, but I hear that with the stock 4.09 axle these cars only have a top speed of 50 mph when they have the OM617 transplanted into them. With the proper gearing, cars with this engine are quick and will easily do over 100 mph. But, yes, going from 4.09 to 3.27 will probably improve the top speed substantially (I want it to do at least 70 mph while having low enough RPMs to not be harming the engine and get the best fuel mileage). The car originally had a 6 cylinder gasoline engine, but the engine had holes in the block, and I have been wanting a turbo diesel fintail for a while.