I think you may have another fault and would also see low figures even if the car was standard.
I have just played with a modified S which had all the right parts but was just down on power, It turned out to be one simple part that was not working correctly, that replaced and the car felt like a new one with much more power.
I have not stated the part that was needed because I would not want to lead everyone to rush out and buy one single item! Correct diagnosis is the key, and can only be done with the right equipment.
Im sure once the additional parts are fitted the genuine fault will become apparant.
6475 rpm / 122.9 mph.......................yes that looks like 5th to me!