Let me re-state my original post above, that is, I have never got more than another .5 degree castor with offset bushings. That's on 4 cars, two mine, two not. I do my own alignments and have done this for friends also. Cars with .5 degree castor seem to drive and ride fine, but we'd like more. If you actually have 5 degrees of castor from factory, that would be extraordinary, but of course entirely possible.

On the aftermarket upper arms I bought, without modification, max castor I could get was 5.5 degrees. That is, one rod arm out as far as safe, the other all the way in. AND, driving around on the street, although not much, you couldn't tell the difference from before. I would do about 95 in the 1/8 mile, and this was done for racing. What I didn't know at the time, is all of this castor was done to fix a car that wouldn't go straight because of rear tire run-out.

Somethings you find out a little too late.

Also, I have had to grind off the back inside of the upper control arm as with the cam turned all the way in board with offset bushing, the arm would hit the inside of the "shock tower".