the 90+ manifold relocates the turbo just a little bit. And that little bit is enough to mess up the alignment of the oil return pipe at the block. The oil return pipe fits into the passage on the side of the block. It is a slip fit; the sealing action is provided by a square O ring.

The misalignment of the pipe going into the block causes the O ring to not be square in the opening, and not seated properly on the shoulder inside the block hole. This would cause an oil leak.

To correct the misalignment, I measure and cut out about an inch of the return pipe. I use high temp 3/4in heater hose to replace the missimg section; and to provide the ability to rotate the lower piece of the return pipe so as to be able to seat the lower piece and O ring squarely in the hole. This restores the integrity of the O ring to block seal. No oil leak. The high temp heater hose is quite capable of handling the temperature of the oil returning from the turbo center section.

While it may not be the most beautiful looking modification, it is very functional.