Building Your Own Catback Exhaust: Is It A Good Idea?

Most auto enthusiasts have thought about building their own exhaust systems at some point. Maybe it’s to save money. Maybe it’s to test out fabricating skills. Maybe it’s because standard after-market systems don’t meet expectations.

Whatever the reason, if you’re thinking about building your own exhaust and you’re reading this, you’re probably wondering if it’s worth doing. The short answer? A home made exhaust can be a good idea if you do it right, but there’s a lot you could do wrong.

Catback Exhaust

You Probably Won’t Save Money

If you’re considering a DIY exhaust system to save money, you’re likely to be disappointed.  It’s rarely the case that an at-home exhaust is any cheaper than buying a pre-fab system.

Vibrant Performance Mandrel 2601

Actually, if this is your first home-built exhaust, you might end up costing yourself more than you would buying a brand name catback.  While you can get cheap mild steel tubing, crush bend it, and throw on the cheapest muffler you can find for a shockingly small amount of money, it’s counterproductive to do so because:

  1. Crush-bent tubing doesn’t flow exhaust gases nearly as well as mandrel bent tubing, which is why you rarely find crush-bends on a newer OEM system, and never find crush bends on an performance after-market system.  You need mandrel bent tubing to maximize performance.
  2. Mandrel bent stainless steel tubing can cost $300 for a simple dual-exhaust system.
  3. If you decide to go with aluminized steel tubing instead of stainless, you can save a few bucks, but you can expect rust and corrosion to attack and destroy your custom system in as little as 2 years.
  4. Cheap, loud mufflers aren’t always bad, but a lot of people aren’t just looking for loud.  If you want a muffler (or pair of mufflers) that balance performance and sound levels, you’ll probably spend another $200-$300.

Without factoring in fabrication time, tools, and various materials, a quality home-built system with mandrel bent tubing and brand-name mufflers costs nearly as much as a complete cat-back exhaust kit.  What’s more, exhaust companies like Magnaflow, Flowmaster, Borla, Vibrant Performance, etc. have been doing this for many years and know how to finely tune an exhaust system for your vehicle.

Do You Know What You’re Doing?

If you lack moderate to advanced welding and fabrication skills, you’re probably better off with a catback exhaust kit.

  • A poor quality weld is more likely to fail and/or crack, causing an exhaust leak that robs power and risks safety
  • Improper technique can diminish stainless steel’s anti-corrosive characteristics, which can hasten rust and corrosion
  • Hanging an exhaust system isn’t as simple as it seems – meshing your system’s mounting points to the factory hangers is logical, but if your system isn’t weight balanced (or has some weaknesses), the factory mounting points might not be what you need
  • Creating your own mounting points isn’t a big deal, but it adds cost and complexity
  • There are specific reasons that OEM and performance catback systems are laid out they way they are.  The car manufacturers and exhaust companies have learned where to place mufflers, bends, etc. to maximize performance

Simply put, a lack of knowledge, skills, or the proper tools could result in a leaky, expensive, and power robbing exhaust system that you’ll either a) spend hours of work fixing and re-doing or b) ultimately replace with a quality aftermarket system.

But I Want A Custom System!

While there are a lot of aftermarket exhaust systems available, heavily customized vehicles often require custom-built systems.  What’s more, there’s something to be said for building your own exhaust, even if you understand that doing so will ultimately be more expensive (and not necessarily better).  Sometimes, custom is the only way go.

If that’s the case for you, then there are some things you can do to make sure your custom exhaust system performs and lasts.

First, look at the factory exhaust system for your vehicle and really study it.  Think of the OEM exhaust as a template for the exhaust system you want.  Replacing the pipes with a slightly bigger size (the precise size of your tubing is a separate conversation – there’s a good guide to exhaust pipe sizing here), better bends, and a freer flowing muffler are all you need to pick up some horsepower.  You don’t have to get fancy to see gains, nor do you have to go really big (in fact, going really big usually reduces power rather than improves it).

Second, let’s talk about pipes (again).  You always want to invest in stainless, mandrel bent steel tubing, regardless of the size.  There are two grades of stainless steel commonly used for exhaust systems: 409 and 304.  304 is the best, but 409 is very good and should last for the better part of a decade.  Crush bends and/or aluminized tubing will disappoint, as they hamper exhaust flow and rust quickly.

Vibrant Performance Oval Muffler 1154

Third, choosing the right muffler(s) is the second most important aspect of any custom system (after choosing tubing size).  Mufflers impact both performance and exhaust note, and going with the wrong muffler can result in a custom system that’s unbearably loud on the highway.  Most muffler manufacturers offer some basic guidance about sound levels, and if you’re looking for something that won’t have a lot of drone, you want to avoid mufflers that use the words “race” or “extreme.”  It’s also good to position your muffler away from the passenger compartment so you don’t have to deal with exhaust drone.

Last, but not least, remember that you’ll get more from a homemade exhaust system if you put more time and effort into it.  If you take the time to study aftermarket and OEM systems available for your vehicle, read up on tube sizing advice, and use high quality components from brands like Vibrant, you’ll probably have a good system when it’s all said and done (assuming of course you have a knack for fabricating).

A self-described “car nerd,” Jason is a automotive columnist who has written for the eBay Motors blog, Motor Car Digest, as well as his own sites TundraHeadquarters.com and AccurateAutoAdvice. With an engineering degree, a full-time job in the automotive parts industry, and a decade of experience working in auto dealerships, Jason brings an interesting perspective on all things automotive.

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