Pontiac Grand Lemans 301cu.in. Headers

[vincent]

Hallo, people! i`ve been looking for a long time for headers which increase hp and fit to my car. But its though to find them. Maybe you can help me.
Pontiac Grand Lemans 1979 sedan, automatic, 301cu. in. engine. Any suggests are welcome (parts, shop, link).
Or you can tell me the Parameters and i will continue searching!

Primary Tube Diameter: ?
Collector Attachment: ?
Collector Diameter: ?
Cylinder Head Port Shape: ?
Primary Tube Length (in): ?
Primary Tube Gauge: ?

Thanks in advance
Best regards from Switzerland