Muffler Delete Vs Straight Pipe: Horsepower, Mileage & Damages

Both muffler delete and straight pipe can provide minor horsepower improvement (5-10 horsepower, depending on the car). Power gain should be more noticeable on higher RPM. 

Both muffler delete and straight pipe does not help a lot with gas mileage but they do provide a much louder car – which can even be uncomfortable at times. 

After seeing countless muffler deletes and straight piped cars (both on my car and my friends’) – I can tell you that both of these options are not the way to go if you want performance or sound.

There are much better options available – which I will also talk about of course!

In this article, I will compare muffler delete and straight piping in various different categories – including performance, sound, tuning, cost and legality. I will even go into technical details like exhaust velocity and backpressure. 

By the end of this article, I am sure you will be 100% clear about the similarities and differences between the two. And even more, you should be able to decide whether to go straight piping or muffler delete or even other better options.

How It works: Muffler Delete Vs Straight Pipe

Muffler delete is where you remove your muffler from the exhaust system and replace it with a steel pipe instead. 

The goal of muffler delete is to have a much louder exhaust noise and improve some horsepower because backpressure is reduced.

Straight piping is where you remove the muffler, resonator and catalytic converter (CAT) from the exhaust system and replace them with a single straight pipe instead. 

The goal of straight piping is to also have a much louder exhaust but also improvements in horsepower and gas mileage because backpressure is reduced significantly. 

Straight pipe exhaust doesn’t have muffler, resonator and CAT.

Muffler delete is more common on street cars because the engine impact is minimal and the gain in exhaust sound is immediate and definitely noticeable. 

Straight piping is more common for track cars. By deleting the catalytic converter, the car becomes extremely toxic. This not only makes straight piping illegal but also dangerous for the driver and bystanders. 

Sound Improvement: Muffler Delete Vs Straight Pipe

Both muffler delete and straight pipe can provide equally significant sound improvement. They both work by removing the sound suppression device from the exhaust. 

In cars where there’s only 1 sound suppressing device, then the sound improvement would be equal.

In cars where there are 2 or more sound suppressing devices installed, then straight piping – which removes them all will be louder than a just muffler delete. 

This case is quite common because some cars come with a muffler and also a resonator installed. 

Do note that the sound improvement here just means that the car is much louder overall. Muffler delete and straight piping will definitely make your car louder but it’s not guaranteed to give you a good sounding car. 

To have a good and aggressive sounding car, you will need to install an aftermarket muffler or exhaust. 

While buying these aftermarket parts, you have the option to review each of them and get the one which gives you the best sound.

After trying out both muffler delete and aftermarket mufflers, I strongly prefer the aftermarket option. I personally like louder and aggressive sounding cars but not to the extreme. 

I have another article here where I talk about what to see when you get an aftermarket muffler. Check it out.  Best Performance Muffler: Which To Get & What To Look For? 

Horsepower Gain: Muffler Delete Vs Straight Pipe

Muffler delete can only give you a minor horsepower gain (about 5 horsepower). Whereas straight piping can give you a little more horsepower at about 10 horsepower. 

To unlock the full horsepower gain from straight piping, you need to tune your car and adjust the fuel injection. I would talk more about this later in the tuning comparison. 

You don’t do muffler delete for horsepower or performance – it’s strictly for sound improvement alone. The 5 horsepower gain from a muffler delete is not noticeable at all. 

And to be honest, 5 horsepower was what I personally got from the dyno after muffler delete. I know a lot of people who don’t gain any horsepower at all. 

On the other hand, straight piping is usually done for enthusiasts that are serious about power gain and who often go tracking with their cars. 

In this case, straight piping with proper tuning makes sense. Especially because it’s only legal on the track but not on the street! 

Exhaust Backpressure: Muffler Delete Vs Straight Pipe

Both muffler delete and straight piping help to reduce exhaust backpressure. Straight piping reduces more backpressure because it removes restrictions from multiple areas like muffler, resonator and CAT.

If you don’t already know, backpressure basically means air pressure coming from the exhaust. 

Long story short, backpressure reduces car performance because it restricts the amount of air that could enter the combustion chamber.

Most performance parts like performance exhausts, muffler downpipe work by reducing this exhaust backpressure.

With muffler delete and straight piping, you are definitely going to have a reduction in backpressure. Though straight piping reduces backpressure event more than muffler delete. 

Is this why backpressure can give even more horsepower than a muffler delete? That’s correct! 

Especially because CAT is an extremely restrictive component – the inside is made of small honeycombs that don’t allow gas to pass through easily. 

You can read more about catalytic convert and CAT delete from this other article – Catalytic Converter Delete 101: Horsepower, Sound & Cost.

Everything in the exhaust can be deleted nowadays…  

Exhaust Velocity: Muffler Delete Vs Straight Pipe

Muffler delete and straight piping does not impact exhaust velocity. This means the exhaust gases will still flow out at the same speed as it was before.

I felt it was important to point out exhaust velocity here because it’s always misunderstood with exhaust backpressure.

Exhaust backpressure, as we discussed, is the air pressure coming from the exhaust. Exhaust backpressure reduces performance, which means the lesser the better.

On the other hand, exhaust velocity is how fast exhaust gases are flowing. Exhaust velocity helps increase performance, which means the more the better.

Exhaust velocity can be increased by having narrower exhaust pipes. In our case, deleting the muffler or straight piping does not help in increasing or decreasing exhaust velocity.

Tune Required: Muffler Delete Vs Straight Pipe

A muffler delete does not need ECU tuning to work. However, straight piping does need ECU tuning  – mainly to turn off check engine light and to adjust air/fuel ratio for maximum horsepower gain. 

The change in backpressure from muffler delete is insignificant. Do not bring your car for tuning just because of a muffler delete. Not only is that unnecessary, you will just be wasting your money.

On the contrary, the change in backpressure from straight piping is more significant than a muffler delete. You are recommended to tune your car after straight piping. 

With tuning, you can turn off the check engine light that comes with straight piping. And you can also recalibrate the air/fuel ratio. 

For a little more money, you could even tune other parameters like removing top speed, removing rev limiter or adjusting the engine torque map altogether. 

Related Articles: How Much Horsepower Gain From Dyno Tune?

You actually could still drive your car normally without tuning after straight piping. However, the CEL will be turned and you risk running lean. 

The CEL from straight piping happens because the CAT is no longer in place. Your car’s oxygen sensor detects the unusually large amount of toxic gases from the exhaust gases and turns on the CEL. 

Is It Legal?: Muffler Delete Vs Straight Pipe

Both muffler delete and straight piping are not legal for street cars. They are both too loud and straight piping is even worse because it’s highly toxic to the environment. 

The only reason a muffler delete is illegal is due to the sound it produces. In many states of the US, a car is required to have at least one sound suppressing device installed. 

Also, in stricter states like California, there’s actually a certain decibel that your car has to operate in. Anything higher than the allowed decibels is illegal.

Technically speaking, you can perform a muffler delete while still being legal. If your car has both resonator and muffler, you can potentially perform a muffler delete and still be legal.  

Provided that your car is still operating within the decibel limit, of course. This is because you still have one working sound suppressing device installed (the resonator) and that’s enough in certain areas. 

Gas Mileage: Muffler Delete Vs Straight Pipe

Both muffler delete and straight pipe do not improve gas mileage. In some cases, gas mileage becomes even worse because drivers unintentionally rev more because of the improved sound. 

If your main concern is gas mileage, then muffler delete and straight pipe are not for you. Try looking into other aspects to improve gas mileage – like keeping your tire pressure right or removing heavy items from the car. 

I write more about muffler delete and gas mileage in this article: Muffler Delete & Gas Mileage (Everything You Need To Know) 

Installation Costs: Muffler Delete Vs Straight Pipe

Muffler delete could be done for about $50 – $100, whereas straight piping could cost about $150 – $200.

Straight piping is more expensive because there are many more components to delete and pipes to bend and fit. 

Muffler delete is quite simple. All you need is a replacement steel pipe to take its place. It’s basically removing the muffler and welding the replacement pipe into place. 

Straight pipe costs more because you need to delete the muffler, resonator and cat. This means you need 3 replacement pipes to take their places. 

You also need to consider other things like exhaust hangers, bending and welding the replacement pipes. 

Here’s a YouTube video showing the procedure on muffler delete. Straight piping is similar but you need to do  it for more components.

If you do decide to do it yourself, you can get an exhaust replacement pipe from amazon here.

Weight: Muffler Delete Vs Straight Pipe

You will have more weight reduction from straight piping than a muffler delete. This is because straight piping removes weight from more components like muffler, resonator and CAT.

Weight is a common subject when discussing car performance. Many car enthusiasts and racers go above and beyond on weight reduction by removing even passenger seats. 

If you care about weight reduction, you are better off with straight piping. However for regular street drivers, weight reduction should not be your concern. It will not give you enough horsepower to be noticeable. 

I personally think you should not do the muffler delete or straight pipe. The sound they make is extremely loud, they get annoying after some time and not to mention they are illegal. 

The only time I recommend trying muffler delete or straight piping is when your car is meant for tracking or off-roading. 

If you want an improved sound for your daily driver, you should look into getting a performance muffler instead. Good ones cost about $80 and you could pick a muffler that gives you the perfect sound. 

If you have more budget, getting an aftermarket exhaust is also another great option – you can gain more performance and a much better sound. 

Here are some articles you should read next:

• 5 Cheap ways To Make Car Louder
• Best Muffler: Which To Get & What To Look For
• Best Exhaust: Which To Get & What To Look For