I think flash tunes are the ideal way to go, but if you have the Dinantronics Stage 3, I'm really not seeing the point to flash tune at this point.
As I posted before, an M235 6MT with the Dinantronics Stage 2, DP, intake, exhaust, and CP made between 366whp and 383whp and 381wtq and 394wtq on a
Dynojet depending on gear and in pretty terrible ambient conditions (85 degree temps) AND without an intercooler. Adding an IC would have allowed the M235 to make more power.
Also, an M235 6MT with the Dinantronics Stage 1 and exhaust made around 340whp and 360wtq on the
Dynojet and in terrible ambient conditions and no IC.
https://www.2addicts.com/forums/show....php?t=1126138
I underline Dynojet because in my experience with modding cars since the mid-1990s, Dynojets are without a doubt the most consistent dynos on the market due to the way they measure power and calculate correction factors. You can compare Dynojet numbers fairly reliably and draw fairly accurate ballpark comparisons about what your car may make in terms of power based on what others have seen with their Dynojet runs.
For example there are a number of Dynojets showing bonestock M235s making around 295-310whp and 315-330wtq depending on transmission and drivetrain with the Xdrives making the least and the RWD 6MTs making the most. Same goes for M2s. They consistently make around 330-340whp and 350-360wtq on the Dynojet.
I have a 6MT M235 running the Dinantronics Stage 2, DP, M2 lower airbox, MPE, and CP. I'm running newer 245/35R18 Michelin Pilot 4S tires and I've got an LSD. I find the car to make way more than enough torque in the low to midrange. Even with the tires warm, I can sometimes light the tires up from a 40mph roll in 2nd. 1st is sketchy from a roll. I actually have better 1st gear traction when launching from a stop. When temps dip below 60 and I'm still on the 4S tires, I can induce spin from a 3rd gear roll at 3000rpms. 1st and 2nd gear are a handful. Point being, I not sure adding more lower rpm torque is necessary. More importantly, the extra torque a flash tune might add below 4000rpms won't be used in a racing situation as full power is not realized in 1st gear due to the dynamics of a turbo and all upshifts land well above 4,000rpms, especially in the automatic cars where upshift entry rpms are near and beyond 5,000rpms. That means even with added torque in the lower rpms, there will be no measurable improvement 0-60, 1/4 mile, etc.
When the S55 M3/M4 came out, they had a ton of low and mid range torque. This made the cars quite a handful and snappy as they came in and out of boost. As the years went on, BMW adjusted the boost strategy to make the torque delivery more linear. The result was a better driving car that actually proved be quicker on the race track because it was easier to control. Just something to think about because linear power delivery was what Dinan touted with Dinantrponics piggybacks.
I haven't seen a dyno for a Dinantronics Stage 3 M235 or 3 series with the N55 EWG. Given the numbers we've seen with the Stage 2 M235s, I would imagine a Dinantronics Stage 3 M235 with a DP, CP, IC, intake, and exhaust is going to be seeing north of 380whp and 400wtq. That's Stage 2 flash tune territory.
If it were me, I'd first be looking into a 300 cell catted DP. I think you'll be quite surprised at the difference in power and improved driveability, turbo response, and sound.