I'm swapping a 5.4 in my mustang and i know for 4.6 mustangs headers won't get you but maybe 5 horsepower it has been dyno proven. But the 5.4 is bigger and i wanted to know if someone has dynoed before and after switching from exhuast manifolds to headers. I know there is a possiblitiy that i will need to do some body work but for now lets just assume that they fit. Also if anyone knows horsepower gains on a bigger throttle body underdrive pullies or any other easy bolt ons please let me know.

 

??

 

I don't believe it makes much of a difference even with the 5.4

95% of guys who do exhaust work just go off the stock headers. Far as bolt ons, I mean it's still primarily the same one's that would add power, just to a varying degree as now dealing with a much heavier vehicle and aerodynamics. Lots of folks do exhaust,gear ratio changes, intake and tune and call it a day.

 

i have bbk shorties on my 5.4 2v on my f150, its been awhile but i belive i gained 8-9 hp. As far as the throttle body and underdrive pullies, ive seen gains as low as 4-5, and high as 9-11 for both apps. And if your look for reasonable performance at reasonable prices i agree with franchi, but if you got money to burn for those lil xp gains go for it

 

Yes, the shorty headers will give you some great bang for the buck.

 

Shorty's generally aren't worth the investment. Longtubes are really the way to go.

At least that is true in the car world. (Vette's Gto's etc.)

 

true if u got the room longtubes are they way to go i would have went longtubes but 97-98 couldnt find any, the shorties were a **** to get in lol

 

I would definatly like to go longtube but it is not an option the pipe would have to come into the car and around my seat and out through the trunk.

 

is this into a mustang? and if so what year?

 

yes a 2002 gt with a t-3650 manual trans and I just recieved the engine today!!!!!!!