I ran both the RPM and the Holley SD in my 470ci 71 Charger R/T With ported 906 / 228@.50 Crower cam and a STOCK 11.75 (2200 STALL) converter 355 rear with tall 275 tire and OEM Thermoquad from a 73 440 . I like the SD better as it fit better and on my car the mid to top power was amazing with no loss of low end power that I could feel. At the track , the SD would et so much better where the Edelbrock seemed dead at 5k . The 60ft was the same with both intakes but the 1/8 was better as well as 1/4 et and mph. On the street the car had just as much low power as befor. BTW , I think mopar only made 11.75 or 10.75 converter ? With this combo (sd intake )my car would run consistant 12.80s at 109 mph with bfg drag radials . That car was the ultimate cruzer . I sold the car a few years back.