new injectors put in by the shop will bring you about $5K. Injectors are about $1500 and install can be upwards of $3500. And there is not such thing as AFTERMARKET INJECTORS. You can only get remanufactured injectors or remans with a % over. I would also check to see if it has the Allison in it. I keep thinking that the first Duramaxes didnt come with Allisons but I someone will have to correct me. As for the lift, it causes undue strain on the front hub bearings, tie rods, idler and pitman arms. They wear out faster. So I would check to see if these are bad before buying the truck.