2008 Ford F-250 Power Stroke - First Performance: Exhaust For the 6.4L

Next, the pipes that go over the axle and the tailpipe were fitted onto the muffler. Fitment was very good, and no bending or muscling was needed to get the system to fit properly.

To give you an idea of the close quarters, this is the exhaust hanger for the tailpipe, which is sandwiched between the frame and exhaust shield for the spare tire. If things don't line up correctly, you're looking at a very hot exhaust that could hit or rub parts.

After the system was in place, the clamps were put back on the muffler and exit pipe.

In the interest of time and a clean install, the tailpipe portion was welded on, but the middle was left with just a clamp so the system could be removed (if necessary) without a Sawzall.

We took the same lap around the block with the new system, and the tailpipe temperatures were significantly lower at 123 degrees. The temperatures were taken without the exhaust tip because the stainless steel tip would throw off the readings. Gibson reports a 100-plus-degree drop in temperatures when towing, and after our quick trip around the block, it seemed reasonable.

The keys to lower exhaust temperatures are the muffler's larger 4-inch design and exhaust venturis (arrow) that mix cool air sooner than the stock tips, resulting in lower exhaust temperatures.

(After) Here are the before and after pictures. The new exhaust gives the Ford 6.4L Power Stroke better looks, more power, and cooler exhaust temperatures. The exhaust note was a tad deeper, but with two turbos muffling sound output, noise levels remained comparable to stock.