I have no experience with either but for the injectors, people that have done it before says it's just be sure to read the instructions over and over until you have an understanding of what to do. 1/2 hour is usually how long it takes ppl to rebuild the 1st injector and they get quicker as they go. As for the intercooler you'll lower your EGT. If you're going with bigger injectors than I would recommend an intercooler! I wish the OBS trucks was intercooled from the factory