TTI Shorty Headers

68 Coronet RT said
68 GTS 340 automatic with a shift kit. Stock block, ported X heads, ported Edelbrock Performer RPM intake with a Edelbrock 650 AVS-2 carb, Hughes Engine cam kit 518 lift 224 duration. 3:73 posi gears. The current exhaust manifolds are the early 68 factory manifolds. Car was built September 8th 1967, Engine has a production date of 6/21/67

I take it that you are describing the car in your avitar.
(Nice car and set up BTW)
I still think the long tube headers would give you some benefit over stock manifolds or the shorties IMHO.