While I was watching the show I was thinking a carb would have made more power, but didn't think they'd try it.

The throttle response of the efi didn't look too good.

My guess for why it made less power is the a/f ratio the efi was chasing wasn't optimum for that combo and the carb was just closer to being "right".

It's a different dyno, so a true apples to apples comparison it's not..... But I tested a street 505 last fall. Rpm heads with a little clean up(way less flow than the TF's), xs290s solid cam with 1.5's, 6bbl.
Made 645tq/590hp.

I would have thought with the TF heads and intake manifold it would have made closer to 650hp, not to mention the extra .100 lift from the hyd roller they used.

I suppose with the carb on it the numbers were pretty close to what I would have expected, and the difference could just be the dyno.