Most of the time you want to avoid the downpipe when routing your drain line. Mine, however, is like yours and runs directly above my dp. I'm running some standard rubber hose and barb fittings for my drain line, and I don't get any leaks from them. I do get a slight leak from above where the drain fitting in the pan is, and it looks like it's coming from my oil pan gasket. If you're running a braided line for a drain, it should be able to hold up against the heat from the dp just fine, but you may want to wrap it with som ThermoShield or that fire jacket stuff. My rubber drain line doesn't touch my dp, but it's pretty close(about 1/4" clearance like yours), and it holds up fine.