Hi, Kuan. Thanks for hanging in there with me.

As I noted earlier, both of those functions use a "cubed" exponent, which intrigues me -- this consistency sort of says to me, it doesn't matter what you're measuring (quarter mile, 0-60, or even the first hundred feet!), but that the horsepower required to achieve any performance improvement must INCREASE by an EXPONENT of THREE.
So, if I get a time (seconds) to a goal (e.g., of 60 mph, or to reach a quarter mile -- it doesn't matter), this improvement takes a cubed increase in horsepower.

So how about 1/((17.4/13)^3) ? The reason for the inverse (i.e., 1/x ) in the formula is that lower elapsed times are indicative of more horsepower, so the horsepower is an inverse function of the time.
This gives me a value of 0.417, which, as a portion of the original horsepower (154) indicates a 64 horsepower increase; which in turn suggests a new output of 218 horsepower.

I'm not scoffing at this estimate, as there is some credibility. 13 seconds is within the ballpark estimate (~12 seconds) of 0-60's for mid-'90s GWagens equipped with the 215 (or so) horsepower M104 engines. So I think I'm in the ballpark.

Thanks.