Had a look at my pipes on it.
The Pro-circuit one would take much more work to get it sitting right, the Akrapovic bolts up just fine.
It's narrower, lighter (being Ti) and less pipe work to make.
(Ant already has one hand on the Pro-circuit)
Decided to go with the YZ front setup.
(Big thanks to 10Antsrees10 for coming up with some Pit clamps and stem)
The nuts and stem are very close to the KLX and KX, the YZ stuff is virtually the same as the KX, just the forks have rebound adjustment too.
A normal Pitbike stem will press into the YZ clamp, just need mix-n-match bearings and spacers and a little machining work then to fit.
YZ left. Pitbike right.
The two top nuts on the YZ stem are the same fit as the KLX. (don't use them anyway)
The pit stem is in, just needs a small spacer, dust/grease seal then the pit bearing. (a bushed KLX top bearing would be ideal)
The top collar needs machining to fit the KLX bearing and to locate into the top clamp. (Mate in work is sorting that out, cheers Alan)
Fingers crossed the length is right, (should be) then i wont have to have a stem made.