It's a D16A6, for sure.
The CRX in general is slow... whether it has 108HP (Si) or 62HP (HF). Almost double the HP, and still just as slow...
Now, to attest to the D-series and it's performance on the cheap, several racers have built 400HP on the stock crank. The rods are the weak point, being pencils and all. Replace those, and the block casting is the weak point, allowing flex in the main bearings. Get a better than OEM girdle, and some proper machining, you can easily get into the 250's and really early 300's as a DD, but it requires serious tuning to keep anything together over 200 or so, and usually boost as well.
Not that any of that matters for our purposes here.
B-swaps aren't great for mileage unless you're going for the torque-heavy B-swaps, like the B18 non-vtec models (USDM Integras) which can run at fairly low RPMs and still accelerate nicely.
I've seen guys claiming high 30's with built D-series, and several claiming mid-30's with B-series street cars.