Yea, these things aren't fast. My Suburban can't get out of its own way at highway speeds, lol. They can be upgraded to make decent power, I know GM makes a 373 ci (or something like that) crate motor that makes about 400 hp, and even with that, these heavy trucks aren't that fast. And the way the 4L60E trans is set up on them is another limiting factor. My truck exists as my daily driver, and to transport my 1 year old twins, wife, and in laws if we need to all go somewhere together, or for longer road trips where the wife can sit in the 3rd row and entertain the kids. I have a smaller SUV that can happily cruise 130 mph all day if I really wanted to, and if I want to go over 160 mph, I have something for that too. But basic mods such as intakes, exhausts, air filters, etc, add negligible if any benefit.