GT Tuning is a company that, um, tunes vehicles in Mexico. They dyno’ed a Jeep Trackhawk and let me just tell you that Mexico City sits comfortably at 2,300-2800m above sea level. In case any of you had questions about the effects of thinner air on car’s performance since Pikes Peak just finished.
Hennessy did a Test of the jeep and it pulled lower torque numbers but slightly higher horsepower numbers. This all in (I suspect) their workshop in Sealy, Texas at around 60m above sea level. 25whp is not a small number, but we could assume that 10-15 are in the error margin, and the real difference is minute.