I love the JB4 in my car. Just google JB4 reviews and your see hardly a bad word written. The JB4 tune has been specially designed for the N54 engine, tech support is great. I've emailed the chap who developed the JB4 tune a few times and in all cases he replies within 24hrs!! If you don't mind doing the install yourself I honestly cannot see any reason why you would go for a traditional remap over the JB4, especially when most remaps actually cost more than the JB4 tune....
I'm running mine on Map 5 at the moment which is a self learning map which apparently adapts to your car, add in cold and hot protection, and adjustable boost limit in 1 and 2nd gear (to help with traction) how much more 'specialised' can you get
