To remove any heat discoloration from stainless, wipe it down with acetone, then use 0000 stainless wool and rub it. Preferably while the tubing is still a bit warm.
You can polish brushed stainless, but it’s a helluva lot of work to do it. Just scan motorcycle slip ons and find one that has a similar inlet diameter to the system and has the length, material, and look you seek.