We tested an Athena 434z, Yoshi 450z, ATK450, Raptor 700 ESR330r on the same dyno w/ dyno tires (Hoosiers)
Raptor 45hp 44tq
Athena 41.15 hp 29.50 tq
Yoshi 40.25 hp 30.15 tq
ATK 40.15 hp 26.50 tq
250r w/ ESR 330power valve 44hp 30 tq if i remember correctly
We ran at 4400 ft elevation
Only yhe ESR and Athena were ported. All ran on pump gas and all had alot of bolt on mods. Just an FYI is all on this partciular day of dyno time.. As stated above, no two dynos are gonna read the same, so comparing them is a waste of time.

In all honesty I'd stroke a Z400 2mm and do the rest in bore to get to 450cc instead of the 5mm stroke and 2mm overbore Yoshimura uses.... The Yoshi grunts harder then the Athena, but the Athena will catch it.. This Yoshi is now ported and the Athena was re-ported on the same flowbench.. The Athena is the king in the real world of Mother Earth of these machines because it revs like nobodys business.. Just wish it had a little more grunt down low "al la 2mm stroke.."