@Xulfiqar
No sir manufacturers are not crazy...they as we all know have to keep a balance between economy,power and most importantly for them emissions...
4hp is nothing but still is a change right ?
As for IAT yes significant because the equation used to calculate the air density involves intake temperature....
Fouling with it MAY give a crisper throttle response...
As for fouling with ECUs goes sir....AFC NEO VAFC etc etc they all are fouling the ECUs...they are not standalone systems...just fouling the ECU....
I am myself against such systems since you can never get the right AFRs matching the V.E curve of the engine with these things...
@SpoonMotorSports
In theory the Oxygen sensor is supposed to trim the fuel maps according to what its reading....if there is a fuel flow problem the O2 reports lean and the required compensation is made on the final duty cycle...but then again one might be of the view that the oxygen sensor can have a range/performance issue on a specific car.....e.g I was tuning a K20/K24 using the stock oxygen sensor in the car which by the way is wideband itself, the datalogs showed that the AFRs where constant(lets say 13.5) in all rpm ranges and loads...but when I got the car on the dyno and plugged in the tailpipe wideband there was a huge lean spike near the VTEC switchover point......So yes nothings perfect
Regards