what needs to be changed in a 72 340 to be like a 70 340?

"In Test 2 we switched to a pair of TTI, stepped headers, 1 5/8"/ 1 ". To say the difference is amazing is a gross understatement!

The power was up 42 hp and torque up 85 ft-lb at only 2600 RPM. And the improvements just kept coming with a maximum improvement for the horsepower at 4900 RPM with 66HP more and the torque was up 72 ft-lb at 4800 RPM"


I knew that stock manifolds would limit your hp/torque, but that's amazing!! I realize that those numbers are from a stroker motor, but I imagine the results would be similar for a high reving 340.