I just got done reading all two posts that reference the HM405 pipes, and much to my chagrine I must say. What I have found out is that they are #1.) rare as all hell, #2.) expensive as all get out, and #3.) not as good as the HM341's. I need a #1 pipe for a 78 K8, and I can't find any anywhere! So much for my luck!
Jeff