You're confusing Performer & Performer RPM, the Performer was nowhere near intended as a replacement for the LD's...the LD's were for drag racing where the stock design, but not component, had to be used if I'm not mistaken. The RPM is a better overall intake for street duty, and I know there's a Dulcich dyno romp that does just that comparo, You gotta search MT/HR TV to find it....this discussion has been done over & over...