Increased shaking/vibration when rolling after installing Powerbox.

the usual problem, but it seems to be happening more frequently since I installed the Powerbox, is there anything I can do?
What about your power consumption readings after installing the Powerbox? In idle, I rarely see a reading of 0-1 liter, usually more - 10 liters or even more. Is this normal?
Does anyone have experience reselling a vehicle that had a Powerbox installed? Are the prices lower, or is the interest also smaller compared to standard vehicles?
Does anyone know how much the letter change costs during the registration process? I'm still considering whether to have it registered at the TÜV or KÜS, and I'm wondering if they will also change the letter in either case.
Thank you in advance.
hello
erwin

Hi

To fix Powerbox jitters, either reduce the power output, or use a different box that allows for a smooth idle. I can absolutely recommend Authal for this.

The power consumption display should be lower when the box is active (the typical design) than when the same driving style and speed are used without the box. This is due to the distortion of the signal used for calculating consumption.

Who or what is the KÜS? I only know the procedure "TÜV changes the document, the registration office issues the vehicle registration document".

'I need to be able to perform Tüv (German vehicle inspection) and AU (German roadworthiness test), but also issue the necessary certificates, so that I can then have the documents registered in the vehicle registration document at the registration office. Will something like DEKRA exist, but smaller?' I think I'm going to the TÜV (vehicle inspection). Then the matter will already be documented in the letter, and there will probably also be an extra charge at the registration office for the entry, and then the price difference of 6 euros between KÜS and TÜV will be offset.
I was able to improve the jitters using the I-potentiometer. It is a SpeedbusterBox.
The energy display shows less during the drive than before, but only when stationary are the jumps larger; I need to test this further.
What are your experiences with selling modified diesels?
Greetings
Erwin