Ok so after a lot of coding, research, datalogs, testing, and more testing, I have validated the 650S can provide just as much gains as the MP4's with tuning on the stock ECU. Coming from an actual owner that daily drives their car, I can assure you, this is even a very conservative tune as I am limited to crappy 91 octane from CA. Ill get into more detail a little bit later but here is the basic specs of the tune and a baseline and tuned dyno I completed last night done on the same day and a few hours apart (in order to pull the ecu and reflash then reinstall). I will be testing and dynoing after this, a set of VelocityAP catted downpipes, and then a Fabspeed sport-x exhaust as well.
Stock Boost: 14-15psi tapering to 13psi at redline
Tuned Boost: 18-19psi tapering to 13psi at redline (will be logging back pressure soon to see if this is a turbo restriction, downpipe restriction, or boost controller restriction that is limiting the available boost at the top of the RPM range)
Timing: Lots of smoothing out and optimizing cruise and midrange timing. At full load, I have actually reduced timing between 2-6 degrees dependent of RPM as stock timing produces knock. As you can see that by tuning for MBT which happens to be less than stock, I was able to still pick up giant gains and lots of area under the curve. This is not all due to boost as you can see around 6000rpm's the car is basically back to stock boost levels.
Fuel: Stock mapping runs way too lean at peak torque and way too rich up top. Getting the car to run a consistent safe AFR I am sure contributed in a big way to the amount of boost and timing the car is able to take and make huge gains.
Knock Settings: Stock is fairly well safeguarded. However, in the interest of even more safety I have tuned the knock maps to be more sensitive to ensure safety.
Speed Limiters: In all active settings, the limiter is already maxed out so no need to do anything there. In Winter mode there is a lower limiter which I left in place. There is also a secret limiter for the VALET MODE! No more worries about valets or others trying to take a joy ride. I set this limiter to 25mph and it works perfect. Punch you PIN in on the dash and your all set until you remove valet mode. Stock, this limiter is set to the max value. I have no idea why they built this feature into the code and did not take advantage of it.
Rev Limiters: Depending on what mode you are in a what gear, stock limiters kick in anywhere from 7000rpms to 8100-8300rpms. I raised mine slightly to the advertised stock limit of 8500. Not much need for this since there is not much power up there.
Launch Settings: Optimizing these are of great value. Raising the RPM slightly to get into boost immediately and reducing the slope of power/torque onset optimizes the power and traction to get off the line. With this I can get off the line with minimal wheel spin and ESC making for better 60' times. Will be testing out drag radials later this year and these settings will maximize the traction, should be very exciting.
Fan Settings: As everyone knows, these cars heat soak like pigs. Hypercar is very right on this topic. I will be doing some cooling system upgrades but in the mean time, I have adjusted fan settings to turn on sooner and spin faster to help things out. With the intercoolers sitting right on top of the turbos and downpipes, I will be wrapping them and then reinstalling stock heat sheilds on the new VelocityAP downpipes that I will be installing soon. I am undecided currently whether or not to fab custom blankets for the intercoolers as this is a plus and minus. While it helps reflect the radiant heat it also will trap heat in. I will likely use NASA style gold foil tape to help reflect the radiant heat off the intercoolers but am skeptical on how much it will actually do.