That looks awesome! Nice work. I haven't flown a 7" yet, this is making me want to though

looks like slow p-term oscilations.
as power to weight ratio isnt that good on big quads, it generaly need very high pid values. i dont own a 7inch but i was watching my buddy having troubles and tune it; i would boost all values by 1/3 to start at and turn off d-min feater.

like the look of that build, looks simply as 5inch racers, stack around four arms, nothing else - nice!
i dont like the look of the practice friendly huge frames that much.

Thanks for the information Banelle and Hugnosed! I will use this to help, bigtime. These bigger quads are definitely more of a challenge to tune than I thought, lol.. time to bust out samurai's tuning guide

That is one oustanding high quality build.

As they say in Jurassic Park "spared no expense".

Wobbles - Without blackbox, its difficult to say.
Frame oscillation is impossible - happens on 5mm or smaller. Mid throttle noise from ESC. I assume you have 1000uF 35V lowESR soldered to ESC?

* You only have 2306.5 on 7". Overproped.
* Your quad is relatively LOW authority.. takes long for weak 2306.5 to spool up big heavy prop.
* Use as light a prop as possible and biblade.
* low authority typically high P, high D, low I. Dont copy, but my quad is P60, I60, D50
* High Iterm "windup" oscillations on roll and pitch.. causes P and D to chase each other. More iterm relax.
* Your P/D ratio may be close to 1.0... before raising D like crazy, take small steps (+5) and ALWAYS test fly 20sec max. NEVER remove/disable dterm filter.

Before I discovered XClass, I thought my **BIG** quads that can easily lift a 2L were "strong". nope.

7incher is Xing2806.5
9incher is BH2812
14incher is Martin4008

The bigger and heavier, the more momentum.
And ofcourse more air = more prop wash.
Prop balance even more important... beatup bent props on big quad are big no-no.

Do try different brand/model props.
But ultimately not all flutter can be tuned out.