X-Pipes ?

Morning All
I am about to send my 88 S4 Auto up to Austin for a complete Intake Refresh and while doing so he will be installing a new X-Pipe.
Having said that.
Are there differences in X-pipes from vendor to vendor. Or are they all basically the same?
In Tn we are required to have Cats. However, I have heard that some people actually hollow out there cats to get by. In doing so would that improve HP? I was told that my car would smell like rotten egg's? What are your thoughts?
Or should I just keep the factory cats in that they have 75K on them.
Lastly, performance cats????

adding an X pipe is a significant power increase to your car. The pipe to have was created by Louis Ott then perfected by Dave Lomas of motorsports in Utah. After significant trial and error and much dyno time the Xpipe thats available today is a bolt on 30hp pipe........928sRus sells them.

Buy the performance cats and remove all the OEM air pump and plumbing.

Found a link for you, Robert. I have taken cars through emissions without the smog pump and passed, but it should be noted that if you're caught then the result will be an automatic fail.

please note the attched link is not the same Motorsports I referenced.

I just bought an X pipe for the GTS with hi-perf cats........ships direct from Utah

Correct. I apologize if there was any confusion. Just pointing out one option.

malcolm;12935 wrote: please note the attched link is not the same Motorsports I referenced.

I just bought an X pipe for the GTS with hi-perf cats........ships direct from Utah

no worries Austin........just want to be clear for the OP

Another part of the X pipe discussion is what to use after the X. On my S4 I have the small/GT type resonators that when fitted with an X pipe/sans cats and a RMB was too loud.........set off car alarms when decellerating in the city. I swapped out the RMB to the OEM rear muffler but that was too quiet so went with a GT rear muffler.......perfect