I saw some show(magazine?) with guys(Spoon or someone in Japan) cuttin tiny slices of piping, and welding them together just so they could get the exact bends they wanted. If I remember right their turbo piping was over 100 pieces welded together, and I also believe they ran something through it to smooth the interior
"You've got a bad turbo"- expert diagnosis by Brice at Alamo Autosports**