If anyone rewrites the ecu software maps, then potentially the flash count of the ecu changes - i think Revo claim not to alter the flash count, maybe ??
If you make a claim then the delaership may check the software itself or the flash count. For simple warranty claims like an injector you would probably get away with it, but if the engine was terminal you can bet MB would look hard at the ecu to check all was as it should be. If you get a single map write over by a tuning company, bear in mond that MB may update the software itself during a service, overwriting any modded map already installed. So you have to go back to the tuning companmy to reinstall again (normally at a cost, and possibly a decent journey away).
Flash rewrite devices are available which allow you to swap from normal to tuned maps via the diagnostic socket - again these may alter the flash count, and Revo don't actually give you back the factory map originally on your ecu, but a generic map they have from another car plus their modded map.
DTUK tuning box - not detectable, as you can remove for any dealer visits. Their simpler box with single connection (maybe not abvaialble for the BE models), basically fools the common rail pressure sensor voltage back to the ecu, with different offsets applied based on the map chosen (normally 4 installed) and the engine revs. These do work and can be fitted and removed in 5 minutes. I've had one on my Golf CR TDI for 6 months now, and its made the car more responsive to drive. The indicated mpg has improved by about 10%, but actual brim to brim calculations says its probably dropped a touch but then you do use the extra oomph !
DTUK latest box uses up to three connections (normally fuel rail pressure, cam position sensor and turbo pressure) - gives a lot more control for the modified maps, but these can be a pain to fit, dependent upon where the sensors are located (i'd need to put my Golf on a hoist and remove undertrays etc).
Andrew at DTUK is very helpful, he sent me all the plots of the various maps and how they modded the fuel pressure voltage signal so i could choose the best map for me. They operate a 14 day no quibble refund, so you basically have a trial period, which no-one else gives on their product in your car. The DTUK boxes use the German DTE box, but software written in the UK by Andrew.
Now don't think for one minute that a tuning box is the bees knees of tuning, it isn't. A proper remp from a knowledgeable company with your car ona rolling road will give better results as they can alter more parameters. But, if like me, you want a solution that the dealer won't know about in the event of a big warranty claim, and are happy with a mild and not the maximum increase, then the tuning box route is still about the only avenue that you can have some faith won't be detectable.
You should of course inform your insurance company, and they may well load your premium by 10% or more !
