When I did mine, I wanted to use the factory tubes too, so I grabbed another one at a local slavage yard. It was only when I realized they weren't long enough that I went with the corrugated tubing from Lowes. Also, if you can't find one at a yard, and don't like the hard corrugated tubing (I'm not too crazy about it either but it works), Gates makes a soft vinyl intake hose in 4".