Once again, I am sorry that it has been so long since I have responded to a message. I read this post and Andy G's with keen interest. I really enjoy learning from you guys. Since I wasn't quite sure what I knew and what I didn't know, I sought data. I am not a car expert, by any means, but I understand something about numbers. Dynatech had previously provided me with a dyno run graph of their test car. The test car was a bone stock automatic except for the headers, cats and X-pipe. I pulled the graph out and looked at it. The max power improvement and max torque improvement were 15.35 HP and 16.19 ft lbs., respectively. I am still not sure what this means. The comparison seems to be between the points on the graphs that correspond to the peaks of the stock run. Based on my use of a ruler, there are many points where the Dynatech run exceeds the stock run by well over 20 HP and 20 ft lbs. Based on the same ruler, the Dynateck torque curve was also higher than stock by 13-15 pounds at both 3500 and 5900 RPM's. The folks at Dynatech told me that they elected to go with a long (32 in) tube and 1 7/8 diameter because there analysis showed that across the spectrum of circumstances, it was the best choice. They also said that they used an unequal length design to spread out the torque improvement. Not long ago, Vette magazine dyno'ed the Corsa Touring system that I had installed with the headers and said that it increased HP by 13 and torque by 10, or thereabouts. If I add the increase for the Dynatech's and the Corsa's together, the HP increase is 28 and the torque increase is 26 without accounting for an interaction between the two. This compares to the 31 HP increase and 23 ft lb. increase with the Kook's/Magnaflows (if my math was right). I am still not sure which is better. Fredo seems happy and I am happy. I am not sure that it matters. My car seems a little more responsive off the line and much more so from 3000-6000. The numbers and the feel seem to agree.