like the 426 hemi, the 429 boss would produce impressive performance,
IF the guy running the car knew how to tune, modify the engine and set up the suspension,
the boss 429 potentially kicked butt.
if you ran the car as it came off the showroom floor,
the boss 429 was not all that impressive simply because the cam it was shackled,
with did not allow it to breath to near its full potential ,
most cars were not geared correctly and ,
most owners were not skilled tuners ,mechanics or drivers.
the same thing could be said of the 440 mopar with the three deuce intake on the road runner vs the dual quad hemi
or the hemi cuda vs the 440 wedge cudas
sox and martin was running in the high 9s back then with a hemi cuda
http://www.mustangandfords.com/featured-vehicles/1711-boss-429-drag-racing-time-capsule/