Headers vs 340 manifolds

Inertia said
Read again, not "across the board", said "up to".

When I install headers, I tune it as nec, make other changes learned thru experience.
I have absolutely no idea what conditions their base was set.

But after years and dozens of cars coming back saying they picked uptime, some 2, some 3, some4 and yes 5/10s.

Did I verify all these dozens of cars, of coarse not, but the resulting happy customers speak volumes.

Maybe your cars woulda picked up more time with a different driver?

Tuning is the key. The Try Y's I put on my 73 340 didn't do much if at all. There were no 60' timers back then. It might have had more low rpm torque but not that I could measure at the track. I didn't change a thing including rejetting the carb or even resetting the timing. That being said, even the smaller 73 manifolds were about the same as the small tube Try Y headers.