355's to 391's how much does it help?

Moparhead said
Did you ever change gear and any et change my firend had a 340 727 71 dart ran 12.7 with 355 and swapped to 391 ran 12.35 ish. Really depends on if your motor makes good hp through 5500-6000, 391 gears and 4 speed is the ideal combo imo.

I made farts made changes at once that year to know what changed but I can tell you I would probably rather have the 3:55 now then the 4:10.