The riser has four bolts that connect it to the manifold. I replaced the gaskets on mine last year when I took the logs off to polish them.
I got my gaskets at Hi-Tech Performance.
In addition, while I had the risers off, I ground out the mis-match between the log and the riser and blended it in to try and help the flow. There was a quarter of an inch difference between the log opening and the riser opening. The grinding and blending gave me an additional 100 rpm on top end.
http://www2.***boat.com/image_center...re_018-med.jpg
If you want a bigger picture, click this (http://www2.***boat.com/image_center...icture_018.jpg)