The emissions legal heads wont flow any better than the nonlegal ones.
I'd go with the Systemx if I were you, or wait until January for the Edelbrock Performer RPM II comes out. I talked to one of their reps at the PRI show over the weekend, and this intake on a NA 5.0L with edelbrock heads made 22hp over the former performer RPM and 5hp more than the Holley! The design of the upper really resembles the Holley as well. Its a nice lookin piece.
Sounds like you've got a good motor plan going, but now whats the current setup or plan for suspension to get all that power down? I get a kick out of it when I race people at the track with these high-dollar motor combo's and I beat them with my ported E7 combo, the looks on their faces when I tell them what it is is priceless
