After getting our Synchronic 40mm wastegate, we decided to upgrade the M5 fittings. After doing some research and development, we had the m5 fittings welded to -4an fittings.

One thing we noticed is that the top ports on the wastegate are very close together. This made the -4an fittings a very tight fitting installation.

We recommend -3an fittings might be a better option, but may not be as easy to weld together as the -4an to barb fittings.

In order to get this mod to work, we had a shop remove the barbs off the fittings, removed the threaded section of the -4an fitting, and had them weld the fittings together.

Once we got the fittings back, we had to modify the very top fitting by grinding the -4an side of the newly welded fitting. We ground enough material to nearly match the original m5 fitting. This allowed us to screw in the fitting into the port while still being far enough to allow a hose end to be screwed on.

Another mod was also needed after we got the very top fitting installed. It required us to grind the lip off the hose end. This allowe us to properly tighten down the hose end to the -4an fittng.