71 Duster 360 turbo build

I'm shocked they are compressed that much. I run a 450lb on my HDK and they aren't compressed nearly that much. However, mine are 12" springs. It almost looks like they would get into coil bind on a big bump.
I avoid big bumps lol. Not sure, might be with all the twins and all the piping. Unless I read the number wrong was on the back side and using a mirror, hopefully not a 10-150.