I saw a while ago there was a giveaway on here, the free item was a drum-shaped box with two ports that were essentially just mandrel bent exhaust tubing.

Does this work well? Are there any downsides?

I'll be fiberglassing some boxes for either a 10" or 12" sub in my trunk but I want to port them, so this seems to be my best option. (Considering I'll need a bend)