When you take out motor insurance cover, you are normally asked if any modifications have been carried out to the car. Installation of a tuning box is a modification which, regardless of the fact that it has been installed after the commencement of the policy, is a modification which must be disclosed to insurers. You are afterall driving a car which you will have advised insurers is 177bhp, but is in essence circa 220bhp. If you fail to disclose this and you have or are involved in an accident, insurers may decline to indemnify you on the basis of non disclosure. Likewise, if a tuning box is added during the course of the warranty, then any damage which normally would be covered under the warranty, may not be. Apart from that, these boxes on the feedback to date do sound good. I would just be slightly concerned that they may shorten the engine life by causing unknown damage. Certainly, i would like more feedback before taking the plunge.