The other common problem is wrong pivot mount on trans.
The z-bar should be sorta square to the engine/trans assembly.
Check a few posts ago. (trans section)
Uncle Bob? Had some decent pics from above of shaft "attitude".
Yeah I did but AFAICT those showed how mine was out of whack and I haven't taken any photos of it since fixing that. I'll see what I can find though.
Basically the Z-bar has to be level and parallel to the frame rail. The two pivots should be directly across from each other.
I bought a TTI z-bar to work with the Doug's headers, it works great, or at least the pedal feels right. It definitely has enough trave to disengage the disc. I set it up using a 1/4" stack of feeler gauges between the TO bearing and the PP fingers (per McLeod's instructions) then tightened it up a little bit after that to get it where it needs to be.