Question?
 

On a quarter mile how much tenths would a 3200/3400 stall take off on my time? Dealers claim 7 tenths on quarter and 2 tenths on 60ft what do you guys think?

Assuming you're going from a stock converter, on a basic full-weight stock or minor bolt-on car ... prob 3-4 tenths in the 1/4 and 2-3 60 ft on drag radials with a decent launch.

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7/10's for a mild converter like that, how bad is a stock one??

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On my LT1 car a 3000 stall, drag radials, and Drag Lites, shaved .5 off of my 60 ft. time alone.

EDIT: Let me correct myself. The stall and drag radials knocked four tenths off of my sixty foot time. I got another .1 after changing from 3.42 to 3.73 gears, and putting on the drag lites.

With tuning, you might get close to what's being said IMO, however, you just said a converter swap. Don't expect too much from any one mod/upgrade. Stall converter and LT's are usually the first upgrades to do ... all a matter of your goals and personal choices of the type of driving you have in mind.