Appreciate HD have a good reputation and not questioning their numbers BUT there are no guarantees with any remap. Its as much about the tuner and what they can get out of it. One tuner will get more out of breathing mods, exhaust, ectuek remap than another. That being said I would not expect to see the results the OP has seen on his Nismo which is less than the 339 It should produce OEM. Given your location I would personally take it along to Mark at Abbey.