[4into4]

I've tried a lot of different carbs between two FFR's. Probably the best is to have a carb built to your specs. The best off shelf carb I found was the QFT, vacuum secondary. Like most of the other things on a carb, the vacuum secondaries need to be adjusted for your application, but when it's right, I found that it outperformed mechanical secondary carbs. A light spring/quicker opening rate (logically) worked best. I know that DP carbs are recommended for light cars, but my personal findings were different. As mrmustang mentioned, go conservative with CFM. I have I have a QFT 650, Q-Series on a 347 making 480 hp, and love it.