When I had access to a milling machine and a lathe I had played around with making some pipe's. I had made three or four of them and tried them but never could get them to really run right. The engine's did run with them but just didnt seem to run like I wanted them two so I stoped making them as it was just a waste of material and money. I think I still have them somewhere as i seen one the other day when I was routing around. But I will say even witht hose machine at hand they still didnt work as well as I had hoped.

Yes you can make them but dont expect the world from them such as huge power gains, infact I would expect to loose power, but maybe you gain some nice sound from it though.