[BarryJI]

I have the same car and the same setup. I agree that the Dinan S1 really sharpens the 228i's performance on the street and I have found that with a (Dinan) performance suspension and shock tuning in addition to the engine tune, the car becomes a genuinely fierce performer in street driving.

I am sure you are right about the power/torque deficit above 5500 RPM but I think that is a very practical peak-power point for tunes designed primarily for the street. To add additional performance beyond that point, I would consider the Stage 4 Big Turbo/Intercooler tune but not only would that be of use only on the track, it would not be street-legal in many states, including here in CA.

I realized pretty fast that there is an effective performance ceiling for the SULEV N26 although I am very happy with the degree to which both engine and suspension tuning can really enhance its street performance and driving dynamics. An S1-tuned 228i with THP will do 0-60 MPH in ~ 4.6 sec and 100 MPH is reached at < 4000 RPM in the higher gears, leaving plenty of torque available for overtaking at that speed and above, especially using sport gearing in the AT. The boost enhancements achieved by the Dinan S1 are also very significant in this kind of driving and really wake the engine up. My modded 228 would not have the high-end grunt needed for the track but it is capable of getting me into a LOT of trouble on the street/highway and I am constantly reeling it in to keep the CHP and the boys in blue away from me.

I have seen many very capable 228s on the track (more than the heavier M235s, in fact) but these are all non-SULEV N20-powered cars. Anyone who buys the N26 to track it competitively will be at a great disadvantage, I fear.