I'm not sure what Dynon uses for the vacuum line, but I had a situation on my car where I installed a vacuum/turbo boost gauge and it would fluctuate. I was using that 1/8" plastic tubing for the line, and I cut a piece of that red tubing like you find on a can of WD-40 or carb cleaner and slipped it inside the other tubing. It took some experimenting to find the correct length of red restrictor tubing, but about one and one half inches should do it.