Turbo Shuffle

I recently acquired a new engine, rb28 vcam setup. After a few hours I've concluded that the car likely has HKS GTRS turbos, making 555 whp on e85 at 1050 m elevation. Anyways, thats not important. The car on the highway surges like it has a turbo shuffle at constant throttle, 3000 rpm. as soon as you get on or off the throttle it goes away. So literally I feel like a dick, passing people, then slowing down, passing them again etc. Can i cause any harm in the engine running it this way or should I spend a few dollars get rid of the low mount bolt on's from probably 10 years ago and install a high mount kit, something a bit newer? Also dont really have 10 grand right now for this problem as the car itself was an absolute ton of money (at least to me)

If you set up a BOV with a soft enough spring you won't build boost against a part throttle on cruise.

Before getting humng up on it being a turbo'/boost flustuation, it's be a sound idea to check the actual manifold pressures during this.

It may actually be omething else, even if there are fluctuations, such as fuelling and/or ignition timing - remember, many "tuners" are focussed on full load 'tuning' and may just have a 'good enough' attitude for actual driveability.

You may find a bit of a jump in some values around the load and speed in question.

Depending where you are, you may pick up additional data by trying to hold similar speeds up and down different gradients, and in different gears.