since i have the x-51 car, would it behoove me to replace the cats with the better ones with fewer holes, would i gain hp , change the sound, other bennies?

 

Yes you will benefit from the cats and even more so because you have the X-51. I think a few guys here with the X-51 did cats, ECU tune and BMC filter and they were at about 400HP.

 

will i see/hear a difference in exhaust sound? i have the relay disconnected so i have the louder noise all the time, wouldn't mind enhancement there...

 

Absolutely! I have the equivalent of the PSE on all the time and with the AWE cats it got louder by ~40%.

 

I've got the same motor as you. I love the high-flow AWE cats. More horsepower, better raspy sound... breaths much better... and you'll find that the cats are the most restrictive part of the exhaust system (especially in an X51 car).

 

thanks for the input, i see the awe's and they look like they just bolt on, do i need remapping or changing out o2 sensors? cel a problem?

 

I had the Awe 200 cell cats, no o2 or cel issues. they bolted on and all lined up really well, a local shop charged me about 2hrs labor.

You could get a tune, I am sure it would help a bit, but your ecu should adapt to the new set up. It will be significantly louder.

 

would it be louder because of my having the pse permanently engaged?

 

No, your PSE should still work as normal. The cats are less restrictive to air flow and noise.