39 Hp up top but look at the torque advantage of the small tubes at 3900 rpm that's 67 Hp in favor of the small tubes! A heavy combo with the right gear and vert probably could et as well or better even if the top end mph wound up lower.

All out race car big headers no doubt....but If this motor was in a heavy dual Purpose car I'd opt for the roll on grunt....That's really not enough head and rpm up top to warrant that big a header unless it was a real light car. Peak torque isn't that much better like a bigger head flow would bring. Maybe an off the shelf 2" x 3 1/2 would be the best balance for this one. And with a full exhaust the peak to peak would likely be less of a spread.

Still an impressive motor!! Like I said I knew the Torque would be massive.