Adding a catted DP should reduce the noise a fair amount and might be all you need.
Another option is to have a resonator installed on the exhaust in the middle of the car.
Vibrant sells a 5x18" SS packed resonator that flows great, it could be installed but could be a clearance issue, my whole system is DIY custom and I made it fit as it was the best one I could find, around $120 or less so not a bad price and will not burn out as SS packing.
If still on the stock turbo make sure to keep the heat shield on it as well.
A valve on the exhaust is only to make noise, I never put on a part that does not make real power, just adds weight and noise unless I really need to hear it and I have considered it for track use as my system is very quiet even when I swap the muffler out for the straight pipe I built.
I would wrap the DP, not really that hard to do, I think I had a 30 ft roll and used it all to ensure really well done, it is double in most all areas, triple in a few, etc....reduces the heat a great deal and warms up the cat faster so it works sooner.
