Let's address the easy facts first:
The 05 GT exhaust system is made up of multiple pieces. The headers attach to the engine and get exhaust from each cylinder. The headers combind the exhaust for each side and are attached to a catted h-pipe. As the name sounds, it's in the shape of an H and contain the catalytic converters need to be run legal on the road. The cat-back attaches to the h-pipe and runs to the mufflers and out the back. This is two pieces. The run to the mufflers and the muffler pieces themselves. They are generally referred to as a cat-back exhaust. The axle-back, is just the muffler piece alone. The axle-back is attached near the rear axle, hence the name.
Now the hard part: Performance.
This is a grey area. If you just read manufacture sites, you will see number that look attractive. However, the 05 has a good stock exhaust as it is (2.5" mandrel bent). I recommend you search this forum and you will see the various opinions on this topic. In all the research I've don't and the people I've talked to, any exhaust change (with the exception of headers) results in a very small, if any, change in rwhp. Assuming that is true, it then becomes a matter of personal preference based on the sound and the look of the tips that you want. Like I said, there are many post on exhaust and allot of manufactures have sound-bytes to give you a feel for the change.
Hope this helps.
__________________ Silver 2005 Mustang GT
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