The outer pipe should be about 10 mm. longer that the inner at the exit. That way gasses exiting the inner pipe create a vacuum that draws cooling air into the front of the outer pipe. The pipe as pictured might work but would run hotter than if it was made properly.

It's hard to tell from the picture but it almost looks like they welded the bellmouth onto the wrong end of the pipe. If it were me I'd contact the disributor/manufacturer and request a corrected pipe. If you had a picture of a proper pipe from their website that would help.

Joe