Get a mechanical secondary Pro-Systems carb. It will blow away that Avenger. Just call Patrick over there and tell him what engine you have and what you want. He'll ask what your zip code you're in to dial in the carb for your local weather. He'll recomend the proper size carb for your engine too.
http://www.prosystemsracing.com/custom.html
The unit I put on my car was the 1040 cfm on a single plane intake Roush 427R, 3.73 rear gear and 28 inch tall rear tires, Tremec TKO with .64 5th gear. The application is extremely streetable, instant throttle response and very accurate form just about any RPM.