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MAC headers and Y-Pipe?

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Old 12-18-2008, 05:20 PM
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Default MAC headers and Y-Pipe?

what are your thoughts on this set up? are they any good? Ive been told that my car is too low to have other longtubes and that these will be perfect and will not hit the ground.are they any good?
Old 12-18-2008, 05:36 PM
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My car will be here in a few hrs ill let u know
Old 12-18-2008, 05:44 PM
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my car made 356rwhp through mac headers off y pipe and flowmaster catback i would say thats pretty damn good for underdrive pulley and a lid with a ls6 intake
Old 12-18-2008, 05:48 PM
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Originally Posted by Gregorya24
my car made 356rwhp through mac headers off y pipe and flowmaster catback i would say thats pretty damn good for underdrive pulley and a lid with a ls6 intake
Yes very nice...looking forward to it
Old 12-18-2008, 07:30 PM
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I had these on my 98 very raspy but made good power had 221 cam and cnc ls1 heads and made 400rwhp
Old 12-18-2008, 08:18 PM
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Originally Posted by regblkss
I had these on my 98 very raspy but made good power had 221 cam and cnc ls1 heads and made 400rwhp
Adding a Flowmaster collector to the Y goes a long way in eliminating the rasp you refer to. I did it when I had the MAC's and it sounded good. The MAC's tuck pretty good under the floorpan for lowered cars.
Old 12-18-2008, 08:26 PM
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Originally Posted by DrkPhx
Adding a Flowmaster collector to the Y goes a long way in eliminating the rasp you refer to. I did it when I had the MAC's and it sounded good. The MAC's tuck pretty good under the floorpan for lowered cars.
they tuck very good, i didnt scrape anything!
Old 12-18-2008, 08:30 PM
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I like'm. I had MAC headers ORP with a 1 Chamber Flowmaster on my 98 Z. sounded bad ***, turned lots of heads. They make good midrange power. I guess thats why they call them midlengths!
Old 12-18-2008, 08:42 PM
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I had them on our show car for a long time and liked them a lot. They tuck up really nice and made very good power.

Mac only makes the off-road version so what we did was weld in a set of Random tech high flow cats which worked really well.

If you need a set, we can set you up with a great price!
Old 12-19-2008, 06:45 AM
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I run Mac mids but they have been modified at the collector with the three bolt setup instead of the ball style connector, suppose to flow better. The ORY has a Flowmaster merge going to a 3" 1 chamber Flowmaster in the stock location with a dump. Sounds real good and doesnt scrape anything. People will bash them because they will make maybe 5-10hp less than a long tube.
Old 12-19-2008, 11:38 AM
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Originally Posted by 99_Z28
I run Mac mids but they have been modified at the collector with the three bolt setup instead of the ball style connector, suppose to flow better. The ORY has a Flowmaster merge going to a 3" 1 chamber Flowmaster in the stock location with a dump. Sounds real good and doesnt scrape anything. People will bash them because they will make maybe 5-10hp less than a long tube.
I've been selling LS1 parts for 10 years now. I remember when the die hard racers switched from Macs to Long Tubes and only dynoed 5-7 HP extra and how pissed they were.

The Macs are a good header. Long tubes are still better but if you want something that tucks up really nice, installs easy and doesn't hit the floor, they are tough to beat.
Old 12-21-2008, 10:37 AM
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Originally Posted by Fast Toys Performance Parts
I've been selling LS1 parts for 10 years now. I remember when the die hard racers switched from Macs to Long Tubes and only dynoed 5-7 HP extra and how pissed they were.

The Macs are a good header. Long tubes are still better but if you want something that tucks up really nice, installs easy and doesn't hit the floor, they are tough to beat.


Bout time there are more people posting FOR mac headers than bashing them!

My car in sig made 399RWHP through mac mids and ORY, there's a build thread and dyno sheet around here somewhere.
Old 12-24-2008, 11:58 AM
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my mac mids helped me knock 8 tenths of a second off mt et and my mph went fro like 77 to 84.xx the i love em they are raspy i have a custon y though.
Old 12-24-2008, 12:00 PM
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The shop car made 427 RWHP through the Mac headers and a Mufflex 4" exhaust system. It sounded great!
Old 12-25-2008, 12:37 PM
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So far I like them alot, No clearance worries either. Hopefully I will be hitting the dyno in a few weeks, ill post up #'s.
Old 12-25-2008, 06:53 PM
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I forgot to mention I ported the inside of the primaries to grind off the weld material left there. I don't know how much it helped, but it was quite a bit in there.
Old 12-25-2008, 09:34 PM
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You can also port the lip out of the primaries where they meet the motor. Opens up the header a good bit. Another little trick we used to do back in the day when longtubes weren't around yet.
Old 12-29-2008, 12:35 PM
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I installed a set up Mac's with the catted y-pipe this summer. I have a FM muffler and I think it sounds great, however there is a lot of interior drone, especially with the windows up. For that reason I will probably be changing the muffler out. My install was a PITA but it sounds like everyone's experience is different. I also have a the dreaded y-pipe rattle since it is bumping up to the driver side floor board. I'll need to get that bent this spring.
Old 12-29-2008, 01:36 PM
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Originally Posted by cobraws6
I installed a set up Mac's with the catted y-pipe this summer. I have a FM muffler and I think it sounds great, however there is a lot of interior drone, especially with the windows up. For that reason I will probably be changing the muffler out. My install was a PITA but it sounds like everyone's experience is different. I also have a the dreaded y-pipe rattle since it is bumping up to the driver side floor board. I'll need to get that bent this spring.
No interior drone here, think thats from your flowmasters.
Old 07-06-2009, 01:33 PM
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def the flowmasters. i already had an slp magnamouth catback and just installed the macs with catted y and the car is no louder than before. sounds slightly better than before but not any louder. might be slightly quieter at idle and slightly louder at WOT but almost no difference.


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