My girlfriend is getting a 1969 Pontiac Grand Prix with a 455 in it swapped from a 1971 Grand Prix and Im looking at putting in headers with at least 2/3/4 piping on it. And I would like to know what kind of Horsepower I will aquire from it. Its running a 14.8 right now and it has stock exhuast manifold with 2 piping to cherry bombs. Someone help me out. Thanks.

 

well---i believe hooker makes a step header like you want but i dont know about that application but they probably do make one.....as far as how much power youll pick up---id say 15hp max---if that----it really depens on how the car is tuned--id run the bigger headers advance the ignition and have someone tune your carb really good and you should pick up a few 10ths---

 

Its not a stock 455. It has an Edelbrock 4 barrel Carberator MSD ignition Accel distributor Moroso spark plug wires Edelbrock Intake Manifold and a couple other things. But I was thinking it would add more than 15 horsepower.

 

it might for a peak--which is like a split second but youll probably only pick up a solid 10hp max---i dont know your car all that well but most cars only pick up a few hp from addong headers----it really depends on how restrictive the stock ones are----you said it had carb and ignition so if the stock headers are really restrictive and you take them off you might see that 15 horse with a good tune of the carb----it all depends....one thing though headers are definatly worth buying for your car.