Re: Do slant heads really make a difference in power?
Yes that is correct.
This mostly helps with detonation and if you don't have squish band like the HT center fire it don't help.
The slant has the advantage of having a squish band, Way higher compression "50% more over std. centerfire", much smaller combustion chamber "5cc vs 8cc and also flipping the head with the plug angle toward the intake directs heat out the exhaust + gives more uniform heating of the cylinder meaning less bore distortion.
I believe you can find all that in Grham's book too. Look how close the plug is to the piston top "close" vs the center fire "below the deck" , So which one has a shorter flame front distance. I ran that PK yesterday and it sounds and feels like a REAL ENGINE.
Anyway my Grubee was fun till i found the PK.