Unless they've been replaced, your injectors will need replacement anyway. Best option is 740's. Problem with turbo replacement is the "while you're in there" stuff, and the "because you're in there" stuff. It adds up quickly. I suggest you search and read on this site, talk to a vendor known on this site, and make a list with $$$$, then add 50% to that. So, if you are tight enough on money to question new injectors, I suggest you reconsider replacing turbos at this time. "Random smoking" might not be all that bad compared to the money you might spend replacing them. P.S. What does "full exhaust" mean? (from your profile)