That cut out is dodgy as hell and if you put that in your front pipe here it would be an instant $10,000 EPA fine
Not to mention it would drop back pressure from your engine leaning your motor out, do it properly and up grade the exhaust with the dump pipes you already have then a matching front pipe with a 3.5" outlet and the 3.5" cat back
3.5" exhausts can be made very quite with good quality mufflers, I had a custom twin 3" into single 4" made for my car and it is quieter then the 80mm jap spec that can off it