exhaust baffle

Hey guys, I am going to build custom exhaust headers, and after a bit of studying I am considering my options. Stock headers are 38mm outside diameter, and they are double pipes so i think inside diameter is around 35mm for example. If I build custom headers from 43mm pipe with thicknes 1.5mm...

Driving an 82 xs400j maxim. Stock exhaust is still on and I am not a fan. However I am a student so I cant afford to buy nice exhaust for the bike so I'm leaning towards the cheapo route: straightpipes. I've been reading other threads on pipes but I cannot find any discussion of throwing these...