Here you can see the preparations for mounting of the exhaust on the chassis.
Below the connection marked with a red line was not exactly 90 degrees.
For that reason I made a very simple jig (an exact parallel and width piece of scrap) to make the spot to glue after sanding 100% parallel to the excaust and also had the correct length:
I also made holes in the mounting spot for putting a dowel in it. This dowel was to reinforce the glue connection:
Then I marked the position on the chassis and drilled holes in it for the dowel:
Thanks for watching.
-- My englisch is bad but how is your dutch?