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What mods to do to a set of Mac headers??

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Old Nov 28, 2001 | 09:51 AM
  #1  
Kilroy's 99 TA's Avatar
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From: Itasca, IL
Default What mods to do to a set of Mac headers??

I'm getting a set of used Macs (finally!) and I know alot of guys do some tweaking to them, what should I do before putting them on the car?
(these will be with the ORP)
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Old Nov 28, 2001 | 10:04 AM
  #2  
TA_2001's Avatar
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From: Dallas,Texas
Default Re: What mods to do to a set of Mac headers??

Here is an old thread that I saved.. about
a mod on MAC's

http://ls1info.com/article.php?sid=108

Do the AIR Restrictor Mod as well..
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Old Nov 28, 2001 | 10:05 AM
  #3  
DRGnFLYZ28's Avatar
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Default Re: What mods to do to a set of Mac headers??

Based on what I've read, you can port & smooth out the ports on each primary tube. I've heard they may have some metal in there that hinders flow. I guess a good port match would help.
Oh, and Jet Hot coat them! I had a MAC y-pipe on my 94 Z and the coating was ok but if I did it again, I'd go Jet Hot.

Good luck!
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Old Nov 28, 2001 | 10:20 AM
  #4  
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Default Re: What mods to do to a set of Mac headers??

[quote]Originally posted by DRGnFLYZ28:
<strong>Based on what I've read, you can port & smooth out the ports on each primary tube. I've heard they may have some metal in there that hinders flow. I guess a good port match would help.
</strong><hr></blockquote>

How much does this porting cost? Im thinking about getting this done on mine...anyone know?
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Old Nov 28, 2001 | 10:25 AM
  #5  
DRGnFLYZ28's Avatar
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Default Re: What mods to do to a set of Mac headers??

I have an air/die grinder and compressor but you can run out and buy a Dremel (pretty cheap) and do it yourself.
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Old Nov 28, 2001 | 01:24 PM
  #6  
2K2 LS1's Avatar
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Default Re: What mods to do to a set of Mac headers??

I ported my set for the 01' basicaly took out most of the inner weld on the primaries. It was pretty sloppy. I don't know what differnece it made, but I am sure it was worth something. Some people modify them to eliminate the air tubes. And alot of people are making their own custom 3" y pipe.
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Old Dec 3, 2001 | 09:38 AM
  #7  
Kilroy's 99 TA's Avatar
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Default Re: What mods to do to a set of Mac headers??

Is it true that with the ORP the headers are really terrible sounding? anything short of putting CATs back on to correct this?
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Old Dec 3, 2001 | 09:47 AM
  #8  
CHRISPY's Avatar
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Default Re: What mods to do to a set of Mac headers??

Install bullets in the Ypipe. You can also expand the collectors or cut them off, extend the collector a little and put in a 3 inch collector. That has picked up 6 or so RWHP on the dyno I think.
Chris
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Old Dec 3, 2001 | 04:35 PM
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jmX's Avatar
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Default Re: What mods to do to a set of Mac headers??

Ported before/after:
http://jmx.car-audio.net/car/macs.jpg
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