Shaving ls truck intake manifolds is one of those DIY projects that separates the "just get it running" crowd from the "I want this to look like a show car" group. If you've ever pulled a 5.3 or a 6.0 out of a Silverado or a Sierra, you know exactly what I'm talking about. Those factory intake manifolds are tall, chunky, and covered in what looks like plastic warts. They're functional as hell—actually flowing better than some of the more expensive car intakes in certain RPM ranges—but man, they are eyesores.
The good news is that you don't have to drop $500 to $1,000 on a FAST intake or an LS6 manifold just to make your engine bay look decent. With a little bit of time, some basic power tools, and a healthy dose of patience, you can turn that "ugly duckling" truck manifold into something that looks sleek, smooth, and custom. It's a labor-intensive process, but the payoff is huge, especially when people pop your hood and can't quite figure out what intake you're running.
Why bother with the truck intake at all?
Before you start grinding away, you might wonder why we even bother with these plastic mountains. The reality is that for most LS swaps, the truck intake is the most practical choice. They are dirt cheap—often free if you bought a complete pull-out engine—and they produce great low-end torque. For a heavy street car or a dedicated truck build, that torque is exactly what you want.
The problem is the aesthetics. GM designed these things to sit under a massive plastic engine cover, so they didn't care about the casting marks, the unused mounting bosses, or the weird reinforcement ribs. When you take that cover off, you're left with a mess of plastic "fins" and vacuum ports you probably aren't even using. Shaving ls truck intake surfaces allows you to keep the performance and the budget-friendly nature of the part while ditching the industrial, unfinished look.
Getting started: The teardown
The first thing you've got to do is strip the intake completely. Take off the fuel rails, the injectors, the throttle body, and any sensors. You want a bare shell. You'll also want to plug the intake runners with some rags or painters tape. The last thing you want is a bunch of plastic shavings or sanding dust getting into the manifold where it could eventually find its way into your cylinder heads.
Once it's bare, take a good look at it. You'll see all kinds of "stuff" that doesn't need to be there. There are mounting points for the original decorative cover, weird structural ribs that look like honeycombs, and ports for the EGR or EVAP systems that many swap guys delete anyway. Your goal is to identify what is actually functional and what is just "noise."
The rough cut: Removing the bulk
This is the part where you get committed. You can't really go back once you start cutting. I usually start with a small reciprocating saw or even a hack saw to get the big chunks off. Those tall mounting pedestals for the engine cover are the first to go. Be careful not to cut too deep; you don't want to compromise the actual plenum wall.
After the big stuff is gone, a die grinder with a carbide burr or a Dremel with a cutting wheel becomes your best friend. You'll want to knock down all those reinforcement ribs. It's going to be messy. You'll have black plastic shavings in your hair, your clothes, and probably your shoes. Wear a mask. Breathing in burnt plastic dust isn't exactly a recipe for a long life.
The trick here is to be methodical. Don't try to get it perfectly smooth with the grinder. Just get it level. You're looking to remove the "peaks" so you're left with a relatively flat surface that you can work with later.
Filling the holes: The make-or-break step
When you shave off the EGR port or some of the larger bosses, you're often left with a hole in the manifold. This is where most people get nervous. If you don't seal these properly, you'll have a massive vacuum leak, and the car will never run right.
There are two main ways to handle this. Some guys swear by plastic welding. They'll take some of the scrap plastic they just cut off, melt it down with a soldering iron or a plastic welder, and "stitch" the hole shut. This is technically the best way because you're using the same material as the manifold, so it expands and contracts at the same rate when the engine gets hot.
The other popular method is using a high-quality epoxy, like 3M 04240 or even something like PC-7. If you go the epoxy route, make sure the area is incredibly clean. Scuff it up with some 80-grit sandpaper so the epoxy has something to "bite" into. I like to use a small piece of plastic as a "backing" inside the hole, then fill over the top. Whatever you do, don't use regular Bondo. Body filler is meant for metal and doesn't like the heat or the flex of an intake manifold. It will eventually crack and pop out, and you'll be right back where you started.
The long road of sanding
If you thought the grinding was the hard part, welcome to the world of sanding. This is where the magic happens, but it's also where most people quit. You start with something aggressive, like 80-grit, to level out the epoxy and the remaining plastic nubs.
You'll quickly realize that the intake isn't flat—it has all these compound curves. You've got to follow those lines. If you sand it too flat in one spot, it'll look "off" once the paint goes on. After the 80-grit has everything level, you move to 180, then 220, and eventually 320 or 400.
At this stage, you might notice small pinholes or low spots. Don't ignore them. Use a tiny bit of finishing glaze or more epoxy to fill those in. The smoother it feels to your hand, the better it's going to look. If you can feel a bump with your finger, you will definitely see it once it's painted.
Painting and finishing
Once you've got the manifold looking like a smooth piece of obsidian, it's time for paint. Because these manifolds are made of a "greasy" plastic (usually nylon), paint doesn't like to stick to them. You absolutely must use a plastic adhesion promoter. Spray a couple of light coats of that first.
For the actual finish, you have a few options. A lot of guys go with a textured "crinkle" black paint. This is a smart move because the texture hides any tiny imperfections you missed during the sanding phase. It gives it a rugged, OEM+ look that fits right in with a clean engine bay.
If you're feeling brave, you can go for a smooth gloss finish or even color-match it to the car. Just keep in mind that a gloss finish is unforgiving. Every little scratch or uneven spot will stand out. Personally, I think a nice satin black or a "cast aluminum" silver looks the best. It makes the plastic look like a high-end aftermarket casting.
Is it worth the effort?
So, is shaving ls truck intake worth the twenty or so hours of labor? If you're on a budget and you care about how your engine looks, absolutely. You're taking a part that costs $50 and making it look like it belongs on a $50,000 build.
There's also a certain pride that comes with it. Anyone can go online and order a shiny metal intake, but not everyone has the patience to hand-sculpt a piece of plastic into a work of art. It's one of those modifications that shows you actually put thought into the details.
When you finally bolt that smoothed-out manifold back onto the engine, hook up your fuel rails, and see how much cleaner the top of the motor looks without all that clutter, you'll forget all about the black plastic dust in your nose. It transforms the whole vibe of the engine bay from "work truck" to "muscle car," and that's a win in my book every single time.