this is why TTi headers suck for power

FWIW, some general rules of of thumbs regarding headers.

1. The tube diameter determines the rpm of the torque peak. Larger diameter higher rpm for the peak.

2. the length of the tubes determines the torque shape on either side of the peak. Longer tubes favors the torque belwo the peak and shorter tubes above.

3. The collector diameter is the same as tube diameter. Collector has the same impact as tube length.

The impact of Tri-Y and step tube designs is greatly influenced by other parameters in the combination. They could help the mid range or not have any significant impact.