Inspector126

I bought a 99 gt 5 speed 4.6. Absolutely love it!!!! I want to put a complete exhaust with flowmaster 50 series. I understand you get more HPwith long tube then shortys. Is this true? Is the price difference justified? Who makes the best brand? I'm told the exhaust will throw an engine code and will need exhaust air sensors. Is this true? If so what kind and how much does this cost? What kind of power gain am I looking at? I also want to put a performance chip in. Which is the best one for this situation and will this throw anengine code? Any information is greatly appreciated.