Originally Posted by JARblue

I expect the main reason the manual states not to use vacuum or pressure bleeding is because the seals in the master and slave cylinders are so shitty and prone to failure. If you keep the vacuum/pressure very low, I would be it works just fine for flushing fluid. But too much pressure will probably mess up the seals and allow air into the system and fluid to escape past the seals.

If you do a CSC delete kit and SS clutch line and HD CMC kit, then you pretty much replace everything in the clutch hydraulic system except for one longer hardline. Very easy to blow out with compressed air during the install. With only the OEM master left, I still saw lots of contaminants in the system on a regular basis. I had to flush clutch fluid twice a year at least because of this.