I melted this 100cell 4" ceramic on 98ron. At 350whp. Replaced with 100cell 4" by 6" metallic. No probs so far. The entire substrate came loose, blocked the exhaust and she popped a intercooler hose, was scary, it was glowing that bad you could almost see through it when the police came to have a look. But that's another story. I got the oval as a free replacement. If your worried about the cat I would go the venom 3" to 5" steel substrate. They fully weld the substrate in and are a quality product. :-D