new exhaust time!
#1
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Hey guys, I've decided to start construction of an exhaust system for the NA. I can't decide on a highflow cat to use. Magnaflow makes a high flow but it seems sort of pricey. I am however going to be using a Magnaflow muffler (part no. 14829 with tip). Piping will be 2 1/4" and I will be legalizing the car for the street, (straight pipe still for the track) ![evilgrin](https://rennlist.com/forums/graemlins/evilgrin.gif)
Any thoughts on a great aftermarket universal high flow cat for a fair price? Magnaflow's high flow catalytic convertor is $94.99 at Jegs.com
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Any thoughts on a great aftermarket universal high flow cat for a fair price? Magnaflow's high flow catalytic convertor is $94.99 at Jegs.com
#2
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Almost all aftermarket cats are "high flow." I really doubt you'll see any variation on a 944. Buy the cheapest one you find. I've seen cats as low as 40 bucks.
#3
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I don't know.. I got a cat from my local parts store, just basic 2.25 inch or whatever inlets/outlets... and it was very restrictive.. like I felt it immediately. I don't think they are all high flow.
#4
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Devon's right, not all cats are high flow. The Dynomax superconvertor I had on the '84 wasn't a high flow. However, it did flow better than the factory one. I'll look into this a little more and check suppliers. If anyone again has reccommendations for certain brand, post away
Thanks in advance.
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#9
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High flow cats are garbage, it is likely you wont be able to pass Cali emissions with one either.
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#10
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I don't mean to jack the post but what would you guys recommend for my 83 if my only concern was noise? I don't need to pass emissions as there are none where I live, so I want something that would give me the most power but not be deafening loud, I don't mind loud just not wake the neighbours for 4 blocks loud.
#11
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Originally Posted by jeff_944
I don't mean to jack the post but what would you guys recommend for my 83 if my only concern was noise? I don't need to pass emissions as there are none where I live, so I want something that would give me the most power but not be deafening loud, I don't mind loud just not wake the neighbours for 4 blocks loud.
#13
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Like Tifo said, stock would be the way to go based on what you want. I have the 2.5 inch SFR catback and its pretty damn loud (though not in a bad way). Its enough to turn heads, even when accelerating slowly. Whether i gained or lost any power, i notice no difference.
All i will say is that it SEEMS to pull better through the mid RPM range now. I noticed no difference (faster or slower) anywhere else. That may just be my mind thinking im going faster because its louder.
All i will say is that it SEEMS to pull better through the mid RPM range now. I noticed no difference (faster or slower) anywhere else. That may just be my mind thinking im going faster because its louder.
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I'm doing the same thing pretty soon. Magnaflow is building a one-off exhaust for me. it's nice to have connections.
Here's what I've gathered so far.
1) The stock system uses a reallllly long cat, a small "coffee can" resonator, and a rear chambered muffler. There will most certainly be a power gain when moving to larger piping, a high flow cat, and a non-chambered rear muffler.
2) Magnaflow/CarSound hi-flow cats will work fine. I've always used them exclusively, often on hard-tuned cars, and never had a problem passing CA smog. If you aren't passing smog with a new cat, then the cat isn't your problem and you have a bigger issue to tackle.
3) Exhaust performance is a trade-off. If you want better flow, you will have to settle for more noise. Period. A quiet exhaust is quiet because it's restrictive. A loud exhaust is loud because it's free-flowing. It's not rocket science! I find a good balance between noise/performance can be found by adding an extra or a larger resonator (round muffler) in-line after the cat. You still get straight-thru flow, but it does reduce the noise significantly.
I'll be using 2.5 piping, mandrel bends, with a "hi flow" cat, round muffler as a resonator, and an oval (non-chambered) rear muffler. All MagnaFlow parts, of course. I'll be using their Standard Aluminized mufflers, as I have no need for stainless in CA.
I'll let you know the results once I can get my car over to MagnaFlow.
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1) The stock system uses a reallllly long cat, a small "coffee can" resonator, and a rear chambered muffler. There will most certainly be a power gain when moving to larger piping, a high flow cat, and a non-chambered rear muffler.
2) Magnaflow/CarSound hi-flow cats will work fine. I've always used them exclusively, often on hard-tuned cars, and never had a problem passing CA smog. If you aren't passing smog with a new cat, then the cat isn't your problem and you have a bigger issue to tackle.
3) Exhaust performance is a trade-off. If you want better flow, you will have to settle for more noise. Period. A quiet exhaust is quiet because it's restrictive. A loud exhaust is loud because it's free-flowing. It's not rocket science! I find a good balance between noise/performance can be found by adding an extra or a larger resonator (round muffler) in-line after the cat. You still get straight-thru flow, but it does reduce the noise significantly.
I'll be using 2.5 piping, mandrel bends, with a "hi flow" cat, round muffler as a resonator, and an oval (non-chambered) rear muffler. All MagnaFlow parts, of course. I'll be using their Standard Aluminized mufflers, as I have no need for stainless in CA.
I'll let you know the results once I can get my car over to MagnaFlow.
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