My Yamiya no numbers (look like HM300)
Have had similar "issues".
It can be a little better if not tighten at front until after tighten at rear.
I think I have used the rear bilt itself to bend the pipe in a better position or another rod.
Yamiya has also added a short steel tube to mate the pipes when mounting them.
I have not used that procedure.
A friend had to do that to align HM 341 replicas from CMS if I remember correct.
If DSS, same manufacturer I guess.
My No numbers that are a little off on 1-2 side.