Dynomax Super Turbos 17748 or 17749 depending on what fits better. They are 2.5" and flow well. Use an X or H pipe and use some more mufflers as resonators.
That's where a long glasspack is helpful.
If you do have to go to single tailpipe it has to be 3". By the time the exhaust has gotten to the back axle it has cooled and contracted some. Huge isn't so necessary back there.
R.