Did your 'friend' degree the cam and have it wind up straight up or did he just 'line up the dots' and call it a day? If that's the case and it wound up being installed somewhere other than what the cam card calls for, well there's your answer.
If it had 4 degrees advance built in it could possibly have been installed correctly by lining up the dots but you would have no way of knowing that unless you degreed it.
I am betting that's your issue here and why you have so much vacuum at cruise. If it was way off, you'd probably be breaking stuff but I bet it's just not optimized. Most likely you will be fighting an uphill tuning battle until you degree it.
I could be wrong though so try to find out exactly what the guy did.
Cylinder pressure is checked by removing the plugs, threading in the compression gauge and cranking the motor 4 revolutions (4 strokes) then reading the highest number. Remember to disconnect the fuel and coil.
