no, you need a 2.25" to 2.25" glasspack and 2" to 2" muffler.

anytime you change the mufflers the car is going to get louder. i suggest you put in a glasspack and run the 3" downpipe with the stock mufflers to see if you like it. it does change the exhaust note a little.

all the GT/GTPs have a Y split to two mufflers.