I know this has been done to death but here goes!
My car had these fitted when it was mapped, the chap then put the old ones back on afterwards because he missed the burble.
The car is a 2.2L with an IHI hybrid turbo etc and is circa 300/300
The thing is it pulls like a train from 3k to 5k then backs of a little until 6.5k then pulls like a train again to 8k
What I want to know is would the headers help fill this little flat spot between 5k-6.5k or am I not going to notice any real gain in torque I would be happy if I had a great dig dollop of Torque in this spot!