You can clamp the muffler flange in a vise and use a propane torch to heat the pipe and bend it. Ace hardware sells the torches and 6mm "all thread" that you can cut to length and use as studs for your motor mounts and manifold attachments. Most auto muffler shops probably won't deal with a pipe that small
My favorite self quote from my first builds is: "6 hour install....my fuzzy butt!!!!!!"
If it can't be broken I'll find a way!
I'm not lost, I'm exploring!