I use the NGK X-Ponder series of plug with internal Bluetooth diagnostic circuitry. Easiest most accurate compression test. Blows my mind what microchips can do now.
With the NGK app in Google's Play Store, Apple or Android, you can real-time monitor head temp, compression, rpm, pre-ignition, spark strength and dwell, plug and coil health, and more right on your cell phone.
Waaay too cool.(edited)