You are in Long Island, so I can imagine the costs being slightly higher there. But I would think it would be closer in line to the costs I see here in the Bay Area of CA.
I paid $1,500 for my install. No tune. This is with the Whipple supplied tune. I sourced 3 estimates...one was for $1,000 and the other was $2,000. I chose the one right in the middle. Shop around.
2012 Mustang GT, Ingot Silver, 6M, 3.73, Brembo.
Whipple 2.9, Flowmaster AT Cat Back 817500.