For fun, I used their test #'s to get the average torque gains as I felt measuring the average horsepower gains was heavily biased to the ones that performed the best at the top of the tach.
The numbers didn't change the finishing order with the exception of the BBK's falling slightly behind the bassani's.
Kooks: 18.69 ft/lbs
MAC: 16.77 ft/lbs
JBA: 16.24 ft/lbs
Bassani: 15.85 ft/lbs
BBK: 14.79 ft/lbs
Hooker: 13.68 ft/lbs
SW: 10.42 ft/lbs
If you remove the 6000 rpm numbers, the Mac's fell off to 4th place behind the JBA's and bassani's so the 1 3/4" tube definitely helped up top but hurt in the lower rev range:
Kooks: 15.29 ft/lbs
JBA: 14.88 ft/lbs
Bassani: 13.20 ft/lbs
MAC: 12.75 ft/lbs
BBK: 11.86 ft/lbs
Hooker: 11.43 ft/lbs
SW: 7.65 ft/lbs
Conclusion: Kooks do make the best power of the ones tested. Mac and Stainless works are a bit short in the midrange but make up for it up top. The JBA's and the hookers fall off at the top of the tach.
The Kooks are probably the best of the bunch but you can get a good portion of the gains with the others as well.
It seems that Kooks has done a much better job on these headers as far as streetability is concerned compared to the Kooks headers I had on my fox-body.