I don't think gutting the CAT is a good idea because of emissions problems. Also I've heard that the back pressure created by the CAT provides better torque, so I'd leave that alone.
Well, you can try a chip, underdrive pullies and or a fan delete mod. Do some searching and you'll see what I'm talking about.
Or if you really have the cash you can do some bigger stuff (OBD conversion, manifold swap, cams, etc.)
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<span style='color:blue'>My ass may be dumb, but I ain't no dumb ass!</span>