You would have to go much smaller on the exhaust side. There are companies out there that will take the stock turbos and bore them out. You could get the stockers modified to support 600+HP.... cost about 700 per turbo. If I don’t go single I will go this route. It’s much cheaper since you can still use the stock manifolds and existing exhaust. Just upgrading the stock turbos to metal turbine wheels gets huge gains do to the ability to raise boost.