Strange Knock in beginning of 3rd

[jackalopeTsi]

i went to the track tonight and got some good results(for me anyways). i still cant seem to get my starts down, but im gonna work on those on thursday. I ran a [email protected]. my profile is updated with all my mods. my best 60 foot was 2.4 and thats where i have problems, Any tips on launching a FWD?

and i noticed i was getting around 7 counts of knock when i shifted into 3rd and it decreased as the RPMs went up. right as i shifted into 3rd and hit the gas @ 4500, i got 10 counts of knock, then it decreased to 0 at around 6400, then started rising again. i know why im getting knock at the higher RPMs, im getting some boost creep. but about the knock at start of 3rd, what could cause this? my tranny grinds in 3rd, but i dont think that would do it, and i do get alot of phantom knock at lower RPMs, but thats just part-throttle cruise situations

 

[DSM90AWD]

i noticed i was getting around 7 counts of knock when i shifted into 3rd and it decreased as the RPMs went up. right as i shifted into 3rd and hit the gas @ 4500, i got 10 counts of knock, then it decreased to 0 at around 6400

Could be slop in the drivetrain (worn CV joint) or your exhaust/downpipe hitting the frame.
When in a higher gear and low RPM let off/on the gas and see if you can hear an audible "clunking"