Why are you trying to replace it? , perhaps if you explained why you need to replace it, someone could point you in the right direction. IE where to locate a stock replacement tube.
Or is there no reason to replace it and you just want to do it for looks? I know its not the louder sound you are after, because you want to keep the stock air box and just replace the piping from that to the throttle body, which wont make the intake any louder.
I would think that the options are limited, Stock, aftermarket CAI/ replacement tube, or home made.
As for home made, I have seen PVC piping used and Exhaust piping used to back yard engineer intake tube's. I wouldn't use either, but if i had to pick i would use exhaust piping.