by TAILSHAFT u mean DriveShaft?
yes

also what max PSI u ran successfully on the A14?
normally a max of around 10psi, but due to the size of the turbo the real limitation was how much boost it could develop. Boost kept rising with engine speed and each higher gear. Basically the higher you revved it the more power it made cause it made more boost. we never got the wastegate to open, for a while I was convinced it was leaking. Maximum boost we ever saw was 12psi @ 7000rpm.

did u check the HP or E.T?
no, unfortunately we never got it to a dyno or 1/4 mile. The lack of boost in first gear would have hurt the 1/4 mile times pretty badly though. I wouldn't like to speculate on it's times but it was MUCH faster than my L18 coupe on the open road. I'm sure the L18 would get a good advantage from the start line, but I also have no doubt the turbo would have run it down VERY quickly.

I kept the turbo gear when we got rid of the car, and bought a couple of cars (1000/B10 coupe, 1200 sedan) with the intention of reviving the turbo engine, but never got around to it.

We'll have to wait and see how NoPSI's sedan turns out - I can't wait. except that I will probably encounter him in my class at some events...hmmm I'm gonna need more power or better gearing or something!