Smoke. It's what's cookin
You shouldn't need injectors unless you go really wild with power. I don't know of many with different injectors. ON the wheels, you should find one that has a high weight rating per wheel. Also if your doing a fifth wheel trailer, E rated tires would prolly be best and you may want to look at add a leaf springs or an air bag system on the rear of the truck. I pu on 17's with 285's on an D rating and they sponge pretty good even at 50 psi. I've been thinking about some airbags. I had to crank my t-bars and that makes it seem like my truck sags easier in the back with a trailer with a lot of tongue weight. ON exhaust, there are several systems to go with. I like my silverline personally.