Better head flow numbers, from a stock LS derivative casting, let alone a modified head.

4.030” test bore
Lift ___.100 _.150_.200_.250_.300 _.350 _.400 _.450 _.500 _.550 _.600 _.650_.700_.750
#1 Int. 74.9 109.4 154.4 193.5 225.3 252.8 274.6 292.7 308.8 321.0 328.7 326.6 310.0 316.6
#1 Exh. 63.6 97.9 126.1 148.7 162.3 178.6 189.6 197.6 205.5 210.7 214.6 217.8 221.2 223.5

321 cfm at .600 lift, which is where a LOT of "mild" LSx cams end up, 210 cfm exhaust

Yes those engines make that HP number, however you know just as well HP and torque are two different things, that bmw engine that makes 500 HP you want to compare to the LS7 makes it at 7750, peak torque ONLY being a whopping 383 ft lbs @ 6300, compare this to the LS7's 475 ft lbs @ 4800, i'd like to see a dyno graph of each overlayed, this also doesnt take into consideration that the LSx i'd have to bet is a HELL of a lot smaller than that V10 bmw engine, making things when considering a swap considerably easier.

Oh that audi 420HP 4.2 ? 420 HP @ 7800 rpm, a whopping 317 ft lbs @ 4500 rpm, compared to the LS3's 436 HP @ 5900, along with 424 Ft lbs @ 4400, that extra 107 ft lbs will be a little bit noticeable, again with an engine that is more compact, and quite possibly weighs less.

You are comparing small displacement high rev'ing vs larger displacement lower reving, airflow in the heads isnt an issue, its just designed to make its power down low using displacement.

On that honda head note, whats impressive is that those numbers were probably (im guessing) obtained using a test bore similar to an actual honda engine, if so those are pretty impressive from such a small bore.