i have orderd a sr 4-1 header for my kia sephia 1.8lt automatic,iv heard that the 4-1 header is best for the manual tranny is this true?if so can some one explain in detail to me why.what kinda hp gain do you guys think i will probabily get with the 4-1.id order the 4-2-1 if they made one but they don't so i kinda have to settle for what i can get.im also going to upgrade my exaust piping to 2 1/2 will i notice a hp from this as well?please every one help me

thanks

 

The header is for both auto and manual.

 

Every motor is different, with betas you wanted to keep the low end since the auto gearing is so damn hi, hence 4-2-1 headders, the Kia auto has better gearing and doesn't suffer so a 4-1 still works on it's auto with out sapping the low end.