I took the first one apart not the one with the warranty, will be sending it back tomorrow.

Just finished installing a C3 Corvette 9" booster, still have some adjustments to make but it works well. This is a rebuilt Delco style with a lifetime warranty.

The 8" had a better feel but a little less power than the Delco 9". The Delco will lock them up but it's a little less responsive, would have to change the pedal ratio to fix that.