Originally Posted by RealQuiet
It can mess with certain sensors and back pressure through the exhaust manifold.
Yes and no. Our vehicles have a 4 stroke engine and are not susceptible to changes in back pressure. Old wives tale. In fact, less back pressure means more power, to a point.
Slight increase in power
Slight change in sound (could be a pro or con)
Simplified exhaust system
No longer emissions legal (may or may not be an issue for you)
Will likely require a custom tune to deal with sensor and computer issues (can and has been done, especially with long tube headers)
You will likely have no noticeable gains for the lack of an expensive piece of equipment.
Stacey David from the TV show Gearz did a segment where he built a vehicle and showed a negligible difference with and without cats on the dyno. He did this specifically to disprove the myth that taking off the cats makes a significant difference and to show that you can have both power and be more environmentally friendly.
It is not worth the hassle unless you are building a serious power toy for off road use.
If it is sound you are after, simply run without a muffler and resonator and then dual tails out the back. Personally I like the sound and it is plenty loud. I really don't think you will see a big difference in sound, although there will be some.
To each his own but I don't think for what you want it is worth the cost and issues. There are plenty of loud, good sounding cat back systems out there.