It doesn’t matter if you are looking to get a header-back, cat-back or axle-back exhaust. The things you should evaluate are generally the same.
I would say piping diameter is the most crucial aspect when choosing an exhaust. Exhaust pipe that’s too wide or too narrow will hurt engine performance. If the piping is too narrow – exhaust gases cannot flow easily. If the piping is too wide – exhaust gases cannot flow quickly. In general, you want the exhaust piping to be wider than stock, but not too wide.
As a general rule, the diameter of an exhaust pipe should be proportional to the horsepower your engine has. Exhaust Diameter in inch = Horsepower / 100. For example, if your car has 300 horsepower, you should get an aftermarket exhaust that’s 3”. If your car has 250 horsepower, you should get an exhaust that’s 2.5”. This is just a general rule. You don’t have to follow it strictly.
Note that this rule applies for the main piping diameter. NOT the diameter of the exhaust tip. Don’t confuse the two. If the sizing is not clearly indicated, please have a chat with the seller to clarify. Extremely important!
There’s no good or bad here – it’s all about preferences. However, it’s always a good idea to know how loud your car will sound before purchasing the exhaust. After all – the sound should be the most noticeable change after you install an exhaust.
Some online stores indicate how loud the exhaust will be. If this information is not provided to you – then I suggest searching on YouTube. I am pretty sure there are guys who have installed it and recorded a before and after noise. You could also check out forum posts to find out how loud the sound will be after installing that specific exhaust.
Don’t expect to gain 100 horsepower by replacing an exhaust – that’s never going to happen. In fact, horsepower gain from changing an exhaust is minimal. Maybe 20 – 30 horsepower if you are lucky. The horsepower gain is also dependent on the size of your engine – the bigger the engine, the higher horsepower you could gain by replacing the exhaust.
That said, it won’t hurt to research about the potential gain before purchasing. If the manufacturer does not tell you, then you can look for answers on forums. Though if you can’t find it, I wouldn’t worry too much about it. Because as I said, the horsepower gain is minimal.
Your aftermarket exhaust should be made of stainless steel and nothing else. Stainless steel is durable and protects your exhaust from rusting. An exhaust system is expensive and it should last a long time. When your car runs through water, the exhaust system will be one of the first components that come in contact with the water. I can’t stress it enough, your exhaust piping must not rust.
To ensure this, look for an exhaust system that’s made of 304 or 409 stainless steel. Both are durable and protect your exhaust from rusting. 304 is a higher grade stainless steel but 409 is more widely used in exhaust systems.
I always think customers review the best indication when buying any parts. Look for an exhaust system that has a rating above 4/5. Also make sure the product has at least 500 reviews – anything less and it could be faked. Other ways you could get customer reviews is through forums. If you can’t specifically find your exhaust model, at least look for reviews on the company that’s producing them.
Ease Of Installation
Performance exhaust is fun and games until you can’t get it installed. This could lead to hours or days of frustration – custom welding and cutting and it’s still not working! To prevent this, ensure below:
- Purchase only the exhaust that’s specifically made for your car model and year.
- Look at the installation instructions – is it straight forward? Can you understand it?
- Look at the product reviews. Customers who review typically mention how long it took them to install.
- Do they include all the necessary parts? Clamping, hangers, etc.