[Drothgeb]

I've made quite a few passes with 75mm primary under various secondaries. Your numbers don't look that bad.

I always pushed the 75mm into the low-mid 40s for best power (numbers depended on the DA), then set the secondary for the total boost. Numbers were normally 42-45/85-90, with 90-100 drive pressure. You're in that ballpark, maybe tighten the gate on the secondary a turn or two.

Your egts are high because of too much fuel. When I was running the 75 w/160hp pump, 5x16s worked best. When I switched to 5x18s, I had to move up to a 80mm primary. Keep in mind though, 1600* isn't good for towing, but it's not bad for a 1/4 mile pass. Much less, and you're leaving some hp on the table.