94mustanggtfast
Active Member
- Joined
- Aug 10, 2010
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so this not technically about a mustang but it is about a 4.6. my aunt has a 2004 mountaineer that threw a bad cat code and she asked me to replace her o2 sensors. i was wondering if her cats are bad how would it affect the car to put a xpipe on it for a mustang or something of that nature it gets 14 mpg so i dont think it would effect that much and we live in sc so no emission laws?