so far the DF 4-1 long tube headers , have shown the biggest increase with true dual 2.5" exhaust with an x-merge pipe.



they produced 68 rwhp more than the standard system, combined with the cold air intake, and a bit of tuning using ls1 edit.

this combination pushed the car to a geniune 12.90 sec pass down the 1/4.

next we will be looking at diff ratios , torque converters for the autos.