i just installed the JDM 4-1 type-r header w/ 2.5 collector,
and it seem like i'm losing HP...
the pick-up is slower i think...
do you guys know why? what did i do wrong when i installed it?
i have a 97 type-r engine JDM B18C.
i also had 2 1/4 piping to the back...
i'm running a b16 ecu with a mugen chip...
anyways, the pick-up seem slower to me...
i don't know why.... what did i do wrong???

 

It felt that same way for me to until in the higher rmp's or on the freeway crusing

 

did you have the cat matched to the larger collector? also you might wanna go to 2.5 piping since you already have the 2.5 header