Installing a new exhaust is always one of the first steps toward better diesel performance. With performance parts coming out for Ford's new 6.4L, we knew it would only be a matter of time before we got a look at an exhaust system for the 6.4L. Gibson Performance Exhaust has just released a new emissions- and exhaust-gas-temperature-friendly system for the '08 Fords, so we followed along on an install to see how it's done.
We had a heat gun to check for temperature drops, which was Gibson's main concern with the new Power Stroke, and we also got a quick look at a dyno sheet that showed a slight power increase across the entire rpm range. The system was very easy to install and could theoretically be bolted on by someone at home in an afternoon. With that in mind, we went to Gibson's shop to see how it was done.
After blasting around the block, we took a heat gun to the stock Ford exhaust and registered a 160-degree-F temperature at the exhaust tips. Gibson's claim was lower temperatures out of the exhaust, so we now had a baseline for that claim. | 
First, the stock exhaust had to be removed. To do this, only one clamp, located at the diesel-particulate filter (DPF), needs to be removed, and then the entire exhaust can be slid out. | 
WD-40 was sprayed on the exhaust hangers to make things move smoothly, and a pry bar was used to leverage the exhaust-hanger brackets. Once this is done, the exhaust can be removed. |
Our test truck turned out to be 2WD, which is a bit lower than the 4WD models-this brought up some clearance issues as we tried to pull the original pipes out over the axle. We even tried lifting up the back to unload the suspension a little, but it didn't work. | 
We were forced to bring out the Sawzall. On 4WD trucks, the exhaust should be removable over the rear axle, but in 2WD models, cutting the exhaust may be necessary to remove the assembly. | 
With the old system removed, the new Gibson muffler was put on right behind the DPF. Its straight-through design offers little in the way of restriction and makes the entire system 4 inches in diameter after the DPF. |