Well it shouldn't really affect your horsepower output. As far as quickness, I guess you could say it depends on a lot of factors, but GENERALLY a manual transmission car is about 1/2 second quicker than a similar car with automatic.
__________________ 66 Coupe - CandyApple Red, 2 barrel 289, C4.
66 Coupe - (father-daughter project). Tangier Orange, 302 with AOD, 17 inch Bullit wheels.
69 F-100 - 351c. Emerald Green Metallic paint. Still "in progress".
68 Barracuda - Rusted out project. 318 in the frame rails for now. Maybe a 360 in the future.
00 Mustang - (son's car) V6, 18 inch Saleen wheels. | 
Tranny change on my 66 
