I relentlessly beat the shit out of my Si because it's too slow, I can't imagine an HF.
A swap isn't going to hurt gas mileage much, a B-series would still get 25-30 mpg which isn't bad at all.

 

43-49>>>>25-30

I find my Si has plenty of power for most situations, I rarely ever floor mine. However, once in a while I do and I'm like I wish I was in the Mustang. I drove an HF once, it wasn't ridiculously slow. It would be fine for a daily driver/fuel miser.

 

I floor mine like whenever I get the chance.
But mine also runs like shit 95% of the time.

 

... maybe it wouldn't if you didn't floor it all the time? :thinking: