I can see a few threads over the last year talking about tuning boxes. Seems like we have a couple of options to choose from: https://tdi-tuning.com/car/audi/s4/...td4-sent-multi-channel-petrol-tuning-box-chip https://www.diesel-performance.co.u...4-354ps-plus-dtuk-mp-t-tuning-box-408ps614nm/ https://www.racechip.co.uk/shop/audi/a4-b9-from-2015/s4-3-0tfsi-2995ccm-354hp-260kw-500nm.html These three seem the most well documented in the UK. They all appear to make about 400bhp on a stock car so I'm assuming they all do exactly the same using the same hardware inputs and the price is the only consideration factor? So my question is: (I fully understand the function of piggybacks as I've used them previously on BMW's) its not clear what differentiates the boxes on the market today e.g. which additional inputs these boxes are using and the level of user adjustment they have? It would be great to hear from someone who as done their due diligence as a consumer and made a call on the right one for their application in order to help me decide. Many thanks!