I just bought my first Mustang and got so excited i didn't really check it out to see if it had real problems. I did test drive it so I was wasn't completely dumb about it. The previous owner put a BBK intake and headers into Flowmasters, what I need to know is would changing the intake and exhaust without increasing the size of the throttle body cause a check engine light to come on? I believe it is a sensor problem cause the lights not on when I start up the car, but after about ten mins at low speed or when I get the car up to 50 -55 mph. Does that sound like it would need a large throttle body. Also another hint is my exhaust smells like gas. I was told from a friend that that's usually caused from not getting enough o2 so the engine is compensating by increasing the gas. i know i should take it and have it read. I just don't want to pay at the dealer cause the shops around me aren't able to read it their equipment will only check back to 96'. So I'll stop rambling. Any feedback would be appreciated.