The boost tubes from intercooler to intake manifold are ready for welding. I fabricated these tubes by cutting out sections of boost tube from an Audi 5000 (gas) car. The boost tubes are 2" mandrel-bent, thin-wall steel.

Just welded one of the intercooler to intake manifold boost tubes. I did this with an oxy-acetylene welding torch.

Fabrication of turbo compressor to intercooler inlet boost tubes. Sorry, part of this picture got a little overexposed.