Welding EGR Cooler - tips?

When I swap in my soon to arrive PD140 turbo, I'd like to future proof my EGR cooler at the same time.

Questions:
- What material is the cooler (aluminum or steel)?
- What position do I weld the butterfly flap (parallel or perpendicular to air flow)?

Anyone?

I believe Franko6 welds them with the flap in the completely open position, then welds shut where the flap hinge post came out so it cannot ever leak. The cooler is made of stainless steel.

They are made of SS and are very sturdy. If they dug up my car 1000 years from now, the only thing that would not have disintegrated into nothing is the EGR cooler.

Put one of Franks reworked coolers on my car at 185K miles. Frank's cooler "kit" came with the new gaskets you will need. It didn't look like it was welded full open or full closed, just someplace in the middle. No more hissing or soot on the back of the engine. No DTC's because the EGR is still functioning 99% as designed and good drivability. Really a permanent fix.

My factory cooler had been leaking since about 55K miles if not sooner. I never did have a DTC related to the leak, just soot, hissing at certain throttle settings and drivability had been declining for a while.