From the given info I can't say it has anything to do with the build, more to do with the combo of the Exedy Twin weight/dimensions and the large jump between 4th & 5th in RPM drop.

Also doesn't seem to happen with everyone considering both Shep & Exedy Twins are the two most popular drivetrain mods on the forums so there has to be another factor involved such as clutch adjustment, installation, ect...

 

Haha should have know that was you right away just got excited. I looked at your pic I'm like that's seeds headlights!!!