Mike Kojima posted on July 14, 2009 16:14
An old-school type performance muffler, which is still very common in speed shops, that has seen better days is the Turbo Muffler. This is a less restrictive version of a stock-like reverse flow muffler. In the old days these were good flowing mufflers, but now the new-jack perforated core, straight through absorption types, have superceded them. Many old school domestic shops will try to sell you one of these as a hot setup but they should be avoided, just like the louvered core glass-pack. Although the backpressure is low, the reverse flow, chambering and baffles reduce velocity and gas column inertia hampering scavenging.
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| The Turbo Muffler is popular with the domestic V8 crowd. It has very low back pressure due to its large internal tubes and simplified baffling. The flow reversal inside its case is bad for maintaining flow velocity though and the perforated core straight through muffler will out power it . |
A popular fashion item is the big exhaust tip. Big tips do nothing for power but can dress up the back of your car. Some enthusiasts like to install ridiculously large tips on tiny stock mufflers or on stock cars. As a warning, this is not cool and the people that really know, even if they know just a little, are not staring at you because your ride is clean, they are really thinking “rice-boy dork” and will joke about you later to their friends! You may even find pictures of your car featured on the web with someone making fun of your car!
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| I think you get the idea. Our apologies to the fans of Bosozoku culture. |
If you are on a tight budget, please save your money and don’t get a big tip until you get the performance exhaust system (and maybe the motor) to go with it. This advice will preserve your dignity. Some big tips feature resonated cores, which quiet the exhaust’s note by a few db. You can spot these with their usually perforated or mesh inner pipes. These big tips are actually functional and we will not laugh at you if you are sporting one of these. As a final reminder, remember that cops like big shiny tips also. Nothing tells a cop pull me over and bust me like a big ass tip.
A disadvantage to the straight through muffler is that it is often louder than a reverse flow type of muffler. Usually a straight though muffler needs a small sub muffler or a resonator to keep the exhaust quiet. A resonator is usually a small, perforated core glass pack placed somewhere in-between the catalytic converter and the main muffler. Like the main muffler, the longer the resonator, the better a sub muffler will be for noise reduction. A Walker Magnum Glass-Pack is a good muffler to use as a resonator. Almost all of the pre-made performance exhausts feature resonators.
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| The Magnaflow muffler we are going to use in our 3 inch SE-R exhaust build is going to be pretty loud so we backed it up with a Magnaflow pre muffler. |
Some good performance mufflers are only available with a semi-universal 2.5” inner diameter. If you have a smaller motor that requires a 2” pipe, it is still ok to use a main muffler with a slightly bigger inside diameter. This larger step up in diameter at the very end of the exhaust system won’t hurt performance and sometimes can help it slightly.
Nowadays even race cars have noise limits as housing encroaches on tracks. Some tracks like Laguna Seca have really low noise limits like 95 db. Perhaps one of the best race mufflers is made by Burns Stainless. It is light, only 4 lbs and is amazingly quiet. Its thin case has to be carefully supported and it needs to be repacked occasionally but it is an amazing piece.
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| Light, rebuildable and quiet, the Burns Stainless race muffler is worth its cost. |
When designing your own custom exhaust it is important to remember to make it as quiet as possible. Loud might be cool to you but remember that a too-loud exhaust is perhaps the number one harassment ticket given to performance enthusiasts by your friendly local law enforcement officer. Don’t ask us how we know this!
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| Burns mufflers can also be had in very small sizes to serve as pre mufflers. |