Due to the increase in the number of muffler and exhaust threads so I figured it's about time to make an ''Official" Exhaust info thread to help everyone out and cut down on the amount of duplicate threads made. I'm not going to crunch the HP numbers and include dyno sheets to build YOU the perfect exhaust, this is strictly for people who simply do not know a lot about the exhaust system and have questions about their cars. However, you can easily build your perfect exhaust system by using this as a resource.
If you have any exhaust related questions that I did not answer, feel free to post a message in this thread!
Factory exhaust systems are designed to evacuate exhaust from the engine & to reduce noise. Obviously. But when we are trying to squeeze out more horsepower, reduce weight, and make our cars sound good, there's no way the stock system will cut it. The exhaust system includes manifolds (headers when aftermarket), catalytic converters, mid pipes, mufflers, and tips; all of which has a big impact on performance & sound!
Stock manifolds are primarily made from cast iron and weigh quite a bit. They are also very restricting so upgrading to headers tends to offer most gain in the power department.
Before I get into popular header choices/brands, you first need to know which headers you want to buy as there are 2 main/most popular styles. Shorty & Long Tubes (LTs). Both offer a gain over the stock set up and are only separated by a 5-10 horsepower difference between each other. Shorties tend to be simpler to install and easier to use with catalytic converters. LTs however have the advantage due to a better collector design and scavenging. The choice is yours, just remember both are much better than stock!!!
Popular header brands are, Kooks
, American Racing Headers
, & Dynamax.
*Some states have very strict emissions regulations/requirements and upgrading to LTs may be illegal. Check with your state laws before buying/installing headers!*
Catalytic Converters/Mid pipes/ORY:
All cars came with catalytic converters as it's mandatory. They clean the exhaust of harmful chemicals and reduce emissions. Without cats, you can free up a few horsepower but in turn you get a strong smell from the exhaust, not to mention in most places in the USA, it's illegal to run without them. To have the best of both worlds, legal and slightly more free flowing, you can buy aftermarket 'high-flow' cats. Most popular are Magnaflow
cats which should be 50 state legal.
If you choose to go catless, you'll need mid pipes also known as an Off Road Y pipe (ORY) which are pipes that connect from your headers into the Y on back.
These play the biggest role in how your car will sound. Once more, the factory muffler is designed with only noise reduction in mind. Choosing which muffler(s) to get depends entirely on YOUR preference. Do you want deep? rumbly? crackly? obnoxious? classic muscle chambered sound? a combination of these??
Some of the popular packed muffler choices are Magnaflow
, Pypes Race Pro
& Dynomax Ultraflow
because of their design. These mufflers usually have a straight through perforated tube inside a case packed with materials like fiberglass, basalt, steel wool etc. to absorb high pitch frequencies, useful for the V6 engines because of their tendency to sound high pitched and thin. On V8s, they sound conservative (depending on case size[smaller cases like bullets or glasspacks have less packing so they are much louder]), have a very deep tone, and roar when the hammer is down.
Bullet style mufflers are smaller, lightweight, and straight through so they flow the best. These are similar to the packed mufflers in that they have a straight through perforated or louvered core tube with a packing around it. Difference is, there isn't a whole lot of that packing so they are much louder and tend to crackle and pop. Some popular brands of these mufflers are Magnaflow Magnapacks, Glasspacks
(Cherrybomb, Thrush, Purple Hornies), Borla XR-1, Pypes M80s, etc.
The other option is chambered mufflers. These mufflers don't flow very well due to their design as they consist of series' of chambers the exhaust must pass through in order to exit. It creates the great classic muscle car rumble because of the exhaust bouncing around back and forth inside the chambers. They sound very good, but again don't flow very well. Popular chambered mufflers are Spintech
, Pypes Street Pro, Hooker Aerochamber
, & Flowmaster 80 series
. Chambered mufflers typically cause a lot of drone (resonance or vibration noises inside the cabin) at certain RPMs. Some more than others (Flowmaster are notorious for it), yet all muffler designs CAN cause some drone.
The overall size of the exhaust tubing plays a big role in not only sound but performance. Tubing too small can choke the engine. The F-Body has a Y pipe format which means that exhaust from two different sides of the motor dump into one pipe that goes all the way back. In this situation, it's ideal to use larger diameter tubing all they way back for best flow.
Cut-outs are used for two purposes. Making your exhaust extremely obnoxiously loud & to by-pass restrictive pipes/systems. Cut-outs can be fully electronic, mechanical, or the manual cap style. In some cases, you may notice loss of low end torque when the cut-outs are open. This may be due to the extreme lack of backpressure thus mostly benefiting vehicles with highly restrictive exhaust systems or extremely modified. However with that said, their horsepower/torque gains can be debated. Of the 3 types of cut-outs, there are 2 styles. Standard and low profile.
Low Profile Cut-Out
What is better, a cat-back system or axle back?
That answer is up to you and how much you have to spend. For a relatively stock or bolt on engine just a muffler change/axle back is best due to cost savings and the sound change. A cat-back system is good for increasing the overall diameter of your exhaust system to improve flow but can cost much more.
What size exhaust should I use?
This depends on a few different factors. Is your engine heavily modified (bored, stroked, cam'd)? What type of induction are you using (nitrous, supercharger, turbo)? Since the F-Body uses a Y system, it's best to go larger (at least 3" back) because you have ALL of the engines exhaust going through ONE pipe which can be restricting. On cars with true dual pipes, 2.5" is perfect, with 3" being overkill unless your engine is stroked/heavily modified and/or using forced induction. Just remember, too small and too large of a pipe can hurt performance!! It's all about maintaining the ideal amount of backpressure!
What is better, full length exhaust to the back of the car or cut off under the car?
Either. The biggest difference between the two is volume. With the exhaust cut off somewhere under the car (before the rear axle is a popular location) the exhaust will be louder due to it's outlet being in the center of the car. One downfall to that is the force from the exhaust exiting can kick up dust and dirt from the road making your car dirty quicker. Exhaust that is routed all the way to the back of the car will be just as loud, however it will be considerably quieter toward the middle and front of the car, because all of that exhaust is being directed behind you. As for performance, they're pretty much the same. If there is a HP gain, it would only be like 1HP and would come from dumping the exhaust as early as possible.
Any questions, feel free to search through our forums to see if the question hasn't been asked/answered already, and check out videos on youtube and in our exhaust clip thread for exhaust tone ideas!