Did you install any O2 sensor with your cat delete as I want to put one in my car but I'm affraid to get CEL.(My Evo is full stock,and I don't want to lose guarantee installing a O2 sensor)I would like to install the Ultimate Racing cat delete.

the UR cat delete is one of the few on the market that do provide the recessed bung for the o2 sensor, eliminating any cel codes. It works great, dont worry, the only thing that will be a challenge to you possibly is the extension of the o2 wires, thats it.

And what is the gain in term of HP? And in term of sound is there a difference?

you pay to play fellas ,but i thaught UR was garunteed no SES light or is that thier high flow??

No I want to buy the Ultimate Racing race cat delete pipe.
This one:
Ultimate Racing 2.5 inch race pipe (off road use only) with gaskets

http://www.z1auto.com/prodmore.asp?m...ust&prodid=481