there are many different companies that make alot of different types of x pipes for our cars, some of the companies from the top of my head is...
-akra (GT4, EVO)
or you can even have a reputable muffler shop fabricate you a custom x pipe to your liking, like making an x pipe with both the cat delete, just the primary cat delete, just secondary delete, making you a straight pipe x pipe where it deletes both the primary, secondary, and the resonators, or even an x pipe with 4 resonators! another option would be to just go with a HFC or test pipes since thats where youll be making the most power!
haha hope that helps!
2011 Porsche 997.2 GT3