Knock at 1-2 shift, why?/Timing advance 1st and 2nd?

[BLK87GN]

I've read about 10 knock problem threads, but not one has explained WHY some of us get knock between the 1-2 shift. One person said boost spike between shifts, what happens if you know that's not the problem, what else could it be?

So i don't have to make another thread, why would you want additional spark advance in the first 2 gears? Everytime i launch the car it wants to knock unless i turn the alky way up, but if i floor it in second it never knocks with the alky turned down. I have the full throttle extender chip, 16lbs of boost, and SMC non-progessive kit.

 

[VadersV6]

Your downpipe could be hitting the frame or a-arm when it shifts. You may also have a torn drivers side motor mount which would make it more severe. Do you have an engine tie strap? Brake torque with a friend watching the engine, and have him see if the engine is tweaking over alot more than it should be, and have them keep an eye on the dowpipe, to see if its smacking anything.
You are under less of a load in 1st and 2nd gear. Less load=less tendency to detonate, which allows more timing. More timing usually means more power...up to a certain point. But sometimes even though the car feels faster with more timing, it may not be faster in the 1/4. Tune with the alky set on a certain level, and keep it there. The spray pattern would be best on 10, and tune around that. Any reason why you're only running 16psi even with alky?
I have the extender as well. I started with alky on 10 and timing pulled all the way out. Im at 20psi. I pulled spool fuel until my O2's looked right in the first couple seconds at WOT....shot for high 600's on O2's. Then I went to normal WOT low gear fueling and pulled fuel until I got KR. Then I added 4% fuel. Then I added a couple degrees of timing, and checked for KR again. If I got KR, I added 2% fuel. If I got no KR, then I'd add 2 degrees more timing. If I started getting KR, I'd add 2% fuel, and so on. The car feels alot stronger with as much low gear timing as I can get, but that doesnt necessarily mean it is faster.