I have the 91 octane version because I am in California and do not have access to 93.
Here’s my first note, regarding the install. If you take the headlight and airbox out, you will have no trouble getting to that lower boost sensor. Me and a friend tried getting to it with the airbox in, and that was a no-go. With the airbox out, I was able to remove and replace the plug within 2 minutes. I didn’t end up needing any special tools.
My initial impressions were overall pretty good. The car felt pretty tame in D mode as usual, but Sport mode is definitely kicked up a notch. That being said, I wouldn’t say the difference is massive. Given that my impressions are nearly the exact same as users such as P.Rico, who already had the P* tune, I have a feeling that the P* on top of this might yield something on top of the TDI. Given that this box simply under-reports the boost levels, if it underreports by some standard offset, it would make sense that the P* + TDI would be better than TDI alone. This is still largely speculation, so I’d be happy to discuss this further if anyone has thoughts.
I tested on a nice chilly day, which was great because I don’t have an intercooler. The biggest difference was felt in 2nd gear, where the car pulls far harder all the way through. With previous 0-60 runs, 2nd gear really fell off, so I’m happy to see this.
As many of you know, these cars are torque limited in 1st and 2nd gear. My theory is that this torque limit is done by the ECU regulating (and lowering) boost in those gears, similar to how boost-by-gear works on crazy tuner cars or the Aston Martin DBS Superleggera for traction reasons. If so, the TDI box would still yield a benefit, as the boost is being under-reported, although without removing this torque limit, the car still isn’t at its full potential. Given that we are already at this gearbox’s torque limit stock, I’ll pass on the Hilton tune.
I didn’t have a spot to wind out 3rd or 4th gear, but I hope to soon. As Bunnspeed has said, the car definitely holds power further through the RPM range, making the engine pull far more similar to a BMW N54 or N55. Part throttle response is still extremely smooth, not that it wouldn’t be, given that it’s just a piggyback.
Either way, I am very happy overall, and am looking forward to more spirited driving. Now I need new brakes…