headers vs manifolds

[fightin irish]

I was thinking of putting headers on my 98 4.0 but if I dont
should I just put on high flow cats and a single muffler with
dual outlets or single with single? thanks for the help.

fightin irish

 

[JimRummy]

The headers will help a decent amount, but from the people I know with headers on their trucks are VERY loud. It's night and day.
I am also curious as to how much benefit/performance increase a high flow cat is...
Also does ditching the resonator affect the performance (+/-) at all or is it just louder?

 

[BlackBII]

This is going to depend on what you have done to the intake side of the motor, and at what RPM ranges you usually use the engine at.

 

[fightin irish]

have done nothing to the intake side and do not want
it louder just a little more performance. going to stop
at meineke around the corner from my house and ask
because they do a whole lot of performance work.
the owner has a 9 sec. mustang.