I replaced the F22B with an F23A and now I notice some slight pinging under light load at around 2,000 - 2,200 rpm. At higher engine speeds and higher loads, no noticeable pinging. I attribute this to two things:
1. Higher compression
2. ECU programming from the old motor and the knock sensor that is not / can not used with the old ECU and wiring harness.

My question is this: would changing the plugs to one or two heat ranges lower help? We used to do that in the old days. I've seen Roader's post and he talked about running premium. Has anyone been able to influence preignition by running colder plugs?

 

Good idea. Looks like PZFR6F is one step colder and it's listed for US-built H22/H23 Preludes and non-US Accords with the same engines. I'm thinking that the slight pinging will go away completely with a drop in ambient temps; I noticed the pinging only ~100F. It may be worth getting a set of colder plugs next summer to see if it makes a difference.