Does it really matter? Use exhaust pipe to make the pipe, and have a flange welded on. C'mon now man. Your making this out to be alot harder than it is. Aluminum has to be welded at a lower temp that some shops can't do. Steel is easier.
ok, then i'll do steel, thx one last question. Wut diameter is the inlet to the intercooler from the turbo? Basicly wut size pipe should i get