-9's will get there IF the setup is well thought out. IE not a peanut exhaust with a silly restrictor on there for example.
-5's will make it easier due to being a tad bigger, but not without a penalty.
If it were me, I'd go -9's and try make the setup as efficient as possible. Using the car for hillclimbs, it'll be faster with the smaller turbos on the standard engine. -5's are too big on a 2.6 IMO.