where to learn exhaust basics?

[fredtoast]

I've been looking for a catback system for my car for quite a while, and I finally decided to go custom. I've researched and found lots of conflicting opinions on how different systems sound. So I've decided to learn more about the basic concepts of exhaust systems so that I can make a decision for myself. Instead of asking how the different ones sound I want to know WHY they sound and flow the way they do. The manufacturers' web sites are not very helpful, and all the dealers tout the brands they sell. I need to find some kind of beginners primer on exhaust systems. I want to know what is in all those cats, cans, and resonators. What difference does the shape of the can make? How about the material from which they are made? Where can I find flow rates? How much difference does a straight thropugh design make? Et cetera.

Thanks to anyone that can point me in the right direction.

[217gsr]

I'll chime in with what I've learned from building my exhaust system. I'm sure other people will add what they have learned.

In regard to the size of the muffler can, the size of the can is directly related to how quiet the exhaust note is, assuming all other things stay the same. On my car, I use a DC 4-2-1 header, 2.5" Carsound (round) cat, 2.5" exhaust piping (not mandrel bent), and a resonator.

I had an internally louvered Dynomax Super Turbo muffler. The construction allowed for the exhaust to be very quiet, relative to the size of the can. On the other hand, it was pretty restrictive, and in the end, those louvers fell apart and I had to have the muffler replaced.

My new muffler is a Borla XS muffler. It has a smaller can than the Dynomax, but at cruising speeds the car is actually quieter. It is louder than the Dynomax when I get on the gas. The Borla is "almost" a straight through muffler. I say "almost" because it is not a straight shot out like on a Magnaflow, but it has a compromise built into it that allows it to be very close to free flowing without being loud and drony like a Magnaflow. I owned a Magnaflow before the Dynomax. That thing droned on the freeway like CRAZY and it was pretty loud. . . due to its straight through design.

Performance wise, if you have no limitations on sound, the Magnaflow probably did the best, followed by the Borla, followed by the restrictive Dynomax (which I would not recommend for a boosted car with power output over 200 whp).

In regards to resonators, I believe the bigger/longer the better to quiet down a loud exhaust.

Flow rates for the Magnaflow are posted on their website, I believe. The Dynomax flowed something like 450cfm (which in retrospect isn't very much). I have no idea how much my Borla flows, but I know it is enough to see my boost DROP in higher rpm levels due to the efficiency of the exhaust.

I hope I helped to answer some of your questions. Feel free to ask me about any other specific aspects of my exhaust system.

[SnowHound]

One word 'Hytech'.

John at hytech is very helpful in answering almost any question you could have, but I'll save you the trouble.

A complete Hytech exhaust system decreases WHP by 1-2 compared to an open header- which is pretty darn respectable. 2.5" piping all the way through, Hi-flow cat, and a "twin Loop" exhaust which is similar too, but better flowing than, the Mugen canister.

Here's a good header review page:
http://www.hondalife.com/articles/bseriesheader.htm

Doesnt' really touch the exhaust piping, but headers are important too.

[fredtoast]

Thanks for the info. I didn't have much trouble chosing a header because there seemed to be a consensus that the 2.5" Kamokaze was the best design for my set up. I've heard great things about hytech. Do you have an email for John? I want to know if they sell just the mufflers instaed of the entire catback system.

[SnowHound]

http://www.hytechexhaust.com/

You can surf their site and then use the 'contact' button to e-mail John directly. I don't know if they sell canisters by themselves, but Mugen does if Hytech does not.

Although, if I remember correctly the Mugen canister has a bottleneck in it whereas the hytech system does not.