So, I'm looking to buy a cat-back exhaust for my 07 5.4 Screw, and rather than start another "which exhaust is best" thread I would like to learn something.

What makes each manufacturer different than the other? From the muffler back most exhausts are pretty the same right? Other than the diameter of the tube and size of the tip for the most part. So, what does Magnaflow do to their muffler thats different than a Flowmaster? Banks different than Roush? and so on and so forth. I understand that sound from the engine enters into the muffler and is deflected in many different directions which gives us the sound that it gives. Please correct me if I'm wrong on that. I just want to understand why one exhaust is different or better than others.

So, if anybody is bored enough to give me a write up and learn me something, I would really appreciate. I have googled, yahooed, and used the search function. I have probably read every exhaust thread posted in the previous 2 years. They all say which is the better exhaust and have the "Dynos to prove it", but what makes that exhaust better is not discussed. I'm also not asking which exhaust is best, I just want some knowledge so that I can make a decision on my own.

All opinions welcome. Thanks in advance.

Ben

 

Material, warranty, performance difference between mufflers (some are straight through like Magnaflow, others use baffles to create a different sound that may cost you some low-end torque.)

Edit: Sorry for the quick response with no write-up, at work.

 

No apologies necessary. Thanks for the reply.

 

What he said, but I'd add that flowbench numbers that allow you to compare the reduction in backpressure over stock would be a performance benchmark to look at. Also look for all stainless steel construction. Who wants to pay big bucks for an aftermarket exhaust that will rust out! Sound levels can vary greatly as well - do you want to sound aggressive only when you get on it, or do you want to annoy the neighbors every morning when you start 'er up?

 

Backpressure, another question I had. Thanks for reminding me. I'm guessing there is a perfect balance in backpressure, or do you try to get the least amount of backpressure possible? Hi flow cats and true duals lead me to believe you would want least amount possible? Keep in my mind I want neither of those mods. I want something that is fairly tame until I want to show some frustration. I have been leaning towards Maggies for this reason, but I thought a little education before the purchase would be a good idea.

 

You want as little backpressure as possible with your exhaust system (high flow cats, straight through mufflers), and you also want as high exhaust gas velocity and exhaust scavenging as possible (mandrel bends, X or H pipe, "reasonable" diameter of exhaust pipe).

Some people throw on an exhaust (high flow cats, Flowmaster mufflers, 2.5" duals) and suffer a "loss of low end torque" and think it's because "Hey my backpressure's all gone! That's where my torque went!" No, it's because of the poor flowing Flowmasters and too big of an exhaust pipe diameter they lower their exhaust gas velocities and all scavenging.

 

So, you want to match the amount of exhaust coming from the engine to the size pipe you are running? Looking for the most efficient way to get the exhaust out of the system? If your diameter is too small you are creating backpressure and too big you are letting the exhaust free flow in the muffler or pipe instead of exiting?

What is scavenging?

 

Right, you don't want an exhaust system too "big" for your application. You'll just end up hurting yourself, less HP/TQ.

Efficiency is exactly what you want. The least amount of backpressure, the highest amount of exhaust gas velocity, and the highest amount of exhaust gas scavenging. It's kind of delicate balance between all three. If you or the mufflershop doesn't know what you/they're doing --- you can potentially leave with a truck that runs worse... As in less HP/TQ.

The size of the exhaust pipe essentially controls the exhaust gas velocity. Too small and you're choking up the exhaust. Too big and you'd hardly feeling the exhaust gases exiting the tip on your hand.

Scavenging is the process in which your exhaust is being pushed/pulled down the exhaust pipe and out of it. Having an H or X pipe evens out the exhaust pulses from both banks of the engine and allows them to cross (more so in an X). Basically pulling the next exhaust pulse along as the one before exits the system.

What are you wanting in your exhaust? How loud? Where do you want it to exit? Duals?

These's just a few simple rules everybody should follow when building an exhaust for these trucks (non-forced induction)...

1. mandrel bends
2. H or X pipe if running true duals
3. no bigger than 2.25" pipes for true duals
4. no bigger than 3" pipe for single outlet

 

Very informative post. Thanks! That really makes it easy to understand.

I'm looking for an exhaust that will give me minimal gains and that sounds refined unless at WOT. I'm not looking to win any races because of my exhaust, so I'm not concerned with how much HP/TQ I will get from an exhaust. With that said I don't want it to hurt performance either. My main concern is sound and looks.

I'm still deciding whether to get dual or single pipes. I'm thinking duals because I think it looks better, but I like to be a little different from everyone else.

I plan to add a tuner, intake, pullies, and fans to add a little more power, and to help pull my boat. These are the reasons I'm not to concerned with the little extra power one exhaust has over another.

 

MudTerrain will always give you a good honest post when it coems to exhausts

I can talk to you about these manufacturers styles though.

Flowmaster

These mufflers are chambered, the majority of their universal mufflers are 3 chambers, and 2 chambers. Chambered exhausts are restrictive for flow, their only positive thing is they sound great. But these days with the towing and hauling trucks do, and with the price of economy, Performance > Sound. Heres some cut a ways of Flowmaster mufflers.

40 series ( loud 2 chamber )


Super 44 ( loud & deep 2 chamber, their best muffler imo, least restricted, best sounding )



Magnaflow

Magnaflow is one of the best performance exhaust systems out there. Free flowing mandrel bents in their stainless exhausts, and direct flowing mufflers which is great for exhaust flow.



Borla is another exhaust manufacturer very similar to Magnaflow, just a higher grade of steel, and a majority of their products are direct flow. They are very costly though.

I would most reccoment a nice Magnaflow cat-back exhaust kit for you. Search their website and browse through the available cat-backs for your truck.

 

One that makes you look like this when you start it up.


Thats my answer

 

Roush Off Road. 'Nuff said.