Catalytic Converters - Advice Needed

[Goat Blower]

If you want to quiet the car and make it look legal for whatever reason, weld a converter casing around a glass pack and put it where the cat goes. Any cat is going to hurt your performance a bit, and will crap out after extended periods of using race gas. You can buy up to 102 octane unleaded(I use 100 octane quite a bit), anything higher than that and even lower than that not labeled unleaded is leaded.