Although this topic has been discussed many times before, I'll throw my 2 cents in. The only time I had experience with running a Cobb ECU on my own car was before Access Port, so granted their maps have likely been updated since. That being said, the Cobb ECU pinged severely through most of the RPM range upon being installed. After a while it would learn around these pings just as pretty much any reflash would, but the result was very rough power delivery with flat spots where the ECU had to pull timing.

Since I've started tuning on my own, I've logged and re-tuned several former Cobb customers running updated "california" maps which also exhibited knock and were no where near smooth. After custom re-tune, the customers gained power and drivability and lost the knock and flat spots associated with the Cobb ecu. Another issue with Cobb maps specifically for 04+ ecu's is the open loop fueling dellay that is programmed into the stock ECU and largely unaltered by the Cobb reflash (although I think after a lot of complaints, Cobb has reduced the issue). There was a very long thread on this topic on nasioc.

I'm in now way a Cobb hater and think that their Street Tuner software and the actual technology behind the access port is a step in the right direction. But as far as their generic maps are concerned, its pretty much hit or miss and so far I've mainly seen misses.

FYI, just because you don't hear knock, doesn't mean its not there. It takes a very sensitive ear and knowledge of what to listen for to hear even the more obvious pings.

Thanks