Making custom exhaust

[lsw11]

Hey,
Im making a set of motorcycles pipes that have step ups in them and want them to be nice and smooth. How do manufactures like martin bros and all those guys get the step ups to look smooth with no imperfections? Do they weld it then grind it down because that seems very time consuming.

Im sorry i couldnt get the picture to upload but like the step ups on this page
Frankie Serrano Designs - Custom Exhausts for Harley/Chopper

Thanks

[coolcat2002]

I think they use this:
Exhaust Tube Step Adapters : Crime Scene Choppers


or this way by La choprods
Although each section slips inside the next we prefer to work a nice radius at each junction rather than simply running a weld bead where one slips into the next. This process is time consuming as each junction is hammer formed by hand over a custom anvil but it provides a much cleaner look.