I would encourage you to push the envelope for N/A, but being N/A I am biased
Although I have a TD04HL-13T sitting on my garage floor
I'm wondering how far you have pushed your AFR without the pre-chamber? I can easily go up to 17.5:1, but loose too much power to pull up hills, so I usually keep it around 16.5:1. This is all on a stock engine with stock tuning. I haven't been able to base line my new combo, because it is too cold. But I'm expecting around 65-70mpg instant readings at 50-55mph.