Porting, Bendable PVC?

I plan on installing an MDF enclosure right below my rear deck with the woofers facing forward... But now my only option to port is straight up through my custom rear deck... Now with the deck and top of the sub box being maybe less then 10" away from each other, now my idea... Cut 2 holes in the rear deck each big enough for 1 4" port, then drill 2 holes in the box and install the 4" port so that it is outside of the box but installed from the inside. Each woofer requires a 4" round port 9" long... can I use flex pvc tube from the home depot for like sewer piping, to connect the two?... I am guessing I should have 2 4" ports each 9" long... but again thats why i'm here to ask questions! Can someone help me clear this up?...

Well I've never really done ports before,  but I know everything I've read about them talk about tuning the sound.   I'm pretty sure the ribs on those flex tubes would really hinder the sound waves traveling through them.   You might could go with pvc hard tube though, you can buy 45's and 90's and straight pipe and make it run straight through the hole in your rear deck. Let us know how it works.Learning the trade one fiberglass creation at a time!