How After-Market Exhaust Systems Can Disrupt Your Car’s Power Curve
When you install a tuned exhaust system, your car, truck, or SUV feels faster and more responsive. If you install a mish-mash of components, start cutting off various parts without understanding their function, etc., you may feel like you’ve wasted your money on a performance part that didn’t improve performance.
Usually, when an exhaust system disrupts your engine’s power curve, it’s because you’ve made one of the mistakes below.
How to Make Sure You Buy The Right Exhaust System or Muffler
1. Don’t go too big. A lot of vehicle owners make a mistake when they upgrade their exhaust system by purchasing exhaust pipes that are much larger than the factory set. With the exception of diesel trucks (which can sometimes benefit from really large pipe diameters), most vehicles leave the factory with the correct size exhaust pipes.
While the factory muffler might be cheap and restrictive, the engineers tend to do a pretty good job choosing the right pipe size. Therefore, stick close to the original factory pipe diameter – don’t add more than a half an inch in pipe diameter unless you’re driving a diesel or you’ve made some major performance upgrades (like adding a supercharger, for example).
Note: Exhaust tip size doesn’t matter when it comes to performance. As long as your exhaust tip isn’t some sort of muffler-tip combo, go as big as you can stand. The size of the pipe between the catalytic converter and the exhaust tip is what matters.
» If you want to know how big your exhaust pipes should be, check out this table of suggested exhaust pipe sizes.
2. Don’t go cheap. The cheapest mufflers on the market are essentially straight pipes filled with cheap fiberglass sound deadening materials. You can probably buy a set with the cash you’ve got in your wallet right now, and honestly they don’t sound too bad when they’re brand new.
Unfortunately, they’re cheap for a reason. When these mufflers get hot (like on a long road trip or a few runs at the track), the fiberglass stuffing inside the muffler starts to melt. Eventually, the stuffing breaks free and becomes an obstruction…and your cheap mufflers get plugged up and start robbing power from your ride. Invest in a good set of mufflers from a brand-name manufacturer (see our list of exhaust system manufacturers).
3. Think about sticking with the factory exit configuration. Are you thinking about adding a dual exhaust system to a vehicle that currently has a single exhaust pipe? If so, you might want to consider the fact that converting a single exhaust system to a dual system isn’t always a good idea.
- If you’re driving a 4 cylinder, adding a dual exhaust system is usually a very bad idea because there’s only one exhaust manifold exit on your engine. Unless you’ve got a very powerful 4 cylinder, there’s not enough exhaust gases coming out of your engine to necessitate a dual exhaust…and even then you probably don’t need a dual.
- Dual exhaust exits only makes sense if you’ve got dual exhaust paths coming out of the motor. If your engine doesn’t have two exhaust manifolds and two sets of catalytic converters (one for each side), then it probably doesn’t make sense to go with a dual exhaust.
4. Building your own system without doing your homework. If you want to avoid paying big money for an exhaust kit, you can definitely build your own. Here’s what you need to do:
- Use mandrel-bent pipes. Mandrel bends are smoother and more aerodynamic than press bends. If the pipes aren’t mandrel-bent, any changes in direction will result in a restriction. The good news is that you can buy mandrel-bent pipes online.
- Choose a muffler made for your vehicle. Mufflers should be chosen by looking at flow rates. Basically, you figure out where your engine makes the most usable power, and then you optimize everything for that point (f you’re a math wizard, you can check out this article on how to calculate muffler and exhaust pipe size). Fortunately, the muffler manufacturers have done the math and testing for us, so all you have to do is buy a muffler that was designed for your vehicle.
- Stick close to the factory pipe diameter. A 2″ dual exhaust system has enough capacity for a 300 hp system. Adding 1/4 of an inch to each pipe adds capacity for nearly 400hp. Going any bigger than 2 1/4 inch pipe diameter is usually overkill (and will often cause your engine to lose power).