Lets point out given problems.
2 - 3° of knock is bad. Engine doesn't like that. Obviously. With that said. 2° of knock will pull roughly 2° of timing.
Now we know the following.
Timing > Boost
The higher you can safely keep your timing without knocking the faster your car will go.
If thw stock GTP has 16° of timing and 0° of KR then it's going to utilize the boost better. And safer.
I am guessing you didn't lose by much? Probably a pretty close race?