***HELP*** N54 2010 exhuast vibratrion

hi, i have a 2010 bmw 335i. I have installed a 2,5inch catless downpipe and supersprint backbox exhuast.

Whenever the car is running in auto, and around 2-3k rpm on moderate acceleration, just as the gear is baouyt to change, i can hear like a horrible sounding vibration which sounds like the exhuast is shaking. sounds like a cheap car. I am running a dinan tune. car sounds fine on full throttle.

can anyone tell me what possibly could be wrong here? does running a catless dp cause this? or is this poor installation work?

thanks