marzo91 , AMEN TO THAT !!
I have 3 of the Brison 3.2's and all run strongly NX 22x8 now getting 7100 rpms 22x10 6900 rpms and steadily increasing with time . I get some RPM changes
from time to time between the 3 engines sometimes as high as 7250 on the 22x8 . There are alot of variables that can change a tach reading
Dont worry about it !! tune for reliability , Not to compete in the RPM bragging game .