if you checked your spark plugs you'll notice 4-5-6 run hotter (look cleaner) naturally being at the back, SR20's run hotter naturally on 3-4.
you can as an option use colder plugs in 4-5-6 to manage heat and zero those trims back, but I'd be leaving it as is unless you have a means of measuring it other than reading the plugs and comparing 1 to 6.
my 2c