The difference in service costs should ONLY be oil and should be around the $50 mark. If they're charging you more because they have to rub the DPF until a genie comes out then they're having a lend of themselves as well as you. They'd be far better off grabbing a girly magazine and rubbing something else in the bathroom (unless they find a "
Village People" album cover more tantalising).
Ultra Tune - or any decent mechanic - will quite likely do a BETTER job at servicing your car, but the big difference will be noticed when you look at warranty issues. Nissan place a fair amount of value on loyalty. A number of members here have had issues fixed outside the warranty period - and the likelihood of that goes down if you service elsewhere. Having a decent dealer to help you is always a bonus - personally I'd go to that other dealer and let them handle the thing.
A Nissan dealership service will follow the log book precisely. For example, you could have a major problem with a component but unless the instructions for the service technician say that they should look in that particular place, they may not notice it. A decent mechanic would simply look over the whole car - the service instructions guide the Nissan mechanic to specific parts only.
Of course, at a good dealership, the mechanic WILL notice other things as well - and when you find a dealer like that, it's probably wise to foster a good relationship with the service manager (and receptionist) there, because then you'll be well looked after (personal experience there - Klosters in Newcastle are great for that).
