i have just installled hooker headers with 3 in y pipe into a 3 inch converter into a 2.5 in catback now i have a poping noise when i get on it is this due to the smaller cat back i need to figure out whats going on any help greatly appericated thanks

 

Popping on accelleration is either a major exhaust leak or you have a wire shorting on your headers.

Popping on decelleration is a lean condition, you need to add and adjustable Fuel Pressure regulator and give the car more fuel.