I think Buschur "found" about 30 whp switching from the cast to tubular mani and T3 flanged Garrett hotside IIRC. My opinion is the hotside and larger T3 flange makes the bulk of the power improvement and not necessarily the equal lenght header. Maybe Dave could give his thoughts.

I had the Buschur cast mani and was happy with it. It gives you a nice stock look if you can hide that giant turbo and waste gate.