The headers go in from the bottom on both sides. Notice the bung for the O2 sensor in the collector area. There's plenty of clearance for easy fitment. The hardest part of the installation is access to tightening the header bolts. It'll need to be done from the top, sides, and the bottom. Having a good assortment of different length 1/4-inch, 3/8-inch drive extensions and universals will help access to the header bolts.