Intercooler Plumbing

[GS guy]

I don't think steel would pose any significant problems, it's been used for ages on air cooled VW turbo engines. Ideally you'd try to work with the original cast pieces and Y section, but not having done this I have no idea if there is any flexibility in re-postitioning the outlet direction. It's too bad really, I think the WRX models have a nice intercooler but too difficult to adapt it to non-OEM applications.

No reason you can't substitute steel connection pieces and flanges though, just make sure the flanges are flat! If you notice excess heat transfer you can always wrap the tubes with insulation. You can also have them ceramic coated for looks, less heat transfer and corrosion prevention. Go for it!
Jeff