Header length equals 400rpm per inch, so it’s not gonna change much.
Personally, I have a metal library here with junk steel tubing with various bends that I can harvest when needed. Handlebars are the best for header bends. Chop out a section and add it in. Remember, only the inside of the pipe is important. Make the transitions seamless inside. As well, after welding be sure to heavily hose out the pipe so you don’t get a lil metal chip surprise into your cylinder.
I generally tack weld things together while on the bike with leather stuffed in the ex port to stop any debris getting in there. You gotta make sure any areas with gas are covered and masked off from sparks with leather pieces or sheet metal in order to not kill yourself. Then once things are tacked you pull it off the bike and do finish welding. (edited)