Some baseline runs on MagnaFlow's chassis dyno gave us a good starting point to work from. We'll run all of our tests on this same dyno to best represent the gains we find. The Cobra's 267hp/276 lb-ft figure at the rear wheels was about what we expected. All tests were run in Fourth gear from 2,500 rpm to the rev limiter at 7,000 rpm.

Upgrading begins with the mufflers. The factory units were cut out to make room for a pair of MagnaFlow units. These particular muffs carry PN 14377. They can be welded up easily to the factory pipes.

Our first re-run on the rollers showed we were on the right track. We found 296-peak horses at 6,000 rpm -that's a gain of almost 20 horses just from the muffler upgrade! Torque numbers increased to 297 lb-ft at 5,000 rpm. That's 20 lb-ft more. It's certainly got a meaner exhaust note, too. We know that's something Ford may not be able to do, but it's our choice now and we choose to bring the noise! The results were so dramatic, we felt compelled to flow-test the Ford factory muffs against the MagnaFlow parts. Check out the flow results on the accompanying chart.

Our next upgrade was further upstream. The catalytic converters and factory H-pipe are all designed as an integral unit, so we'll upgrade both at this time. Removal is pretty straightforward, with the need to remove the oxygen sensors (circled) prior to dropping the converter/H-pipe assembly.