I think the turbo back, unlike the cat back, needs a tune to avoid CELs.
Laborsmith
I went with this one, Amazon.com: Vibrant 11620 J-Style Oxygen Thread: Automotive
but I think this one would be good too, Amazon.com: Vibrant 11619 J-Style Oxygen Sensor Restrictor Fitting with Adjustable Gas Flow Inserts: Automotive
I went with the first one only because other members have used this one and they said it does work. The second seems to have more versatile settings to change amount of exhaust flow going to it but a shorter runner length. I would of picked the second if someone stated that it worked for them.