paulm007 - Just a bit of info from the main dealers standpoint - A non-educated dealer will tell you tales of how these upgrades destroy your warranty and will make you car difficult to re-sell blah blah. I know of at least four of my customers who have had their cars Revo'd and still come into us for servicing. As long as you turn the re-map off when you come in (i think you can get a plug-in thingy that turns the new software on and off) we will never know. I know a customer who has a GTI 1.8T 150ps Revo'd to 212ps that still comes in for routine servicing and no-ones any the wiser. I don't know what can be done woth the Mark V but as long as you revert to normal when bringing in for service, we'll not know!
Hope this helps!
