I did a google search and found the following dyno results for Dinan Stage 3 on F10.
***********.com/content.php?2498-Dinan-Stage-3-F10-550i-(N63-twin-turbo-V8)-tune-hits-411-horsepower-to-the-rear-wheels
Assuming 20-25% loss to wheels, the numbers seem close to Dinan claims for Stage 3? (yes, I understand you are only at Stage 2... but between Stage 2 and Stage 3, there is only a 20hp difference ... provided you got the exhaust). Obviously, I don't have Dinan software installed and can't speak from experience. Would be interesteing if more folks got their Dinan dyno'd