MTXL or AEM = complete ready to use. Guage (has electronics built in) and sensor are sold together.
MTXL claims to be a water resistant gauge and you can hook up your laptop to it and do a data log (AFR only).
If you want to add RPM into the mix you need to start thinking about using one of their "Aux" boxes which can handle other sensor values. The prices will start to add up quickly.
Do you have a 950 or 990?
'07 KTM 990 Adventure - Black