MAC MID Headers a good choice?
MAC MID Headers a good choice? Might do a Mac Mid header setup for my 96z28. Any good prices on them anywhere?
good ground clearance
good fitment/ plug access
1 5/8 header helps with low rpm torque, 1 3/4 seems a bit big for my bolt on LT1 which usually sees rpms less than 4000.
Not sure if I would want to keep my air/egr or delete it all and clean up the engine bay a little. No emission checks here in Michigan. I have read that even with Mac Mids that bolt on LT1's can still get 290-300rw.
good ground clearance
good fitment/ plug access
1 5/8 header helps with low rpm torque, 1 3/4 seems a bit big for my bolt on LT1 which usually sees rpms less than 4000.
Not sure if I would want to keep my air/egr or delete it all and clean up the engine bay a little. No emission checks here in Michigan. I have read that even with Mac Mids that bolt on LT1's can still get 290-300rw.
We put Mac mids on my brothers 94 formula when he 1st got it, that was like 15 yrs ago. I kinda remember the plug access was decent, and the hp gain was ok. I went straight to LTs on my 96 and there was a pretty good difference between the 2 cars hp. With almost identical mods my car with LTs was faster. Header installs on lt1s aren't that bad, but if you're going to do it you might as well go LTs. Especially since you don't have to worry about emissions.
I'm running MAC mid's and have no ground clearance issues. The y-pipe is about 1/2" lower than my UMI tubular k-member. Plug access is outstanding. I just use an open end ratcheting wrench and a regular plug socket. Car sounds great, makes great power 
I know for sure that mac mids make good power over stock manifolds, maybe a few less top end hp than long tubes but I bet they are just as good in the low and mid range.
I would consider long tubes if heddman or summit actually makes a good fitting 1 5/8 LT header for the LT1 that doesn't smash the floor board when you floor it!!! It just sounds like all the trouble of LT's aren't worth the hassle when mid length headers have very few issues?
Also can you change the clutch in a m6 without pulling the header out of the way? I know some cars have this issue.
I would consider long tubes if heddman or summit actually makes a good fitting 1 5/8 LT header for the LT1 that doesn't smash the floor board when you floor it!!! It just sounds like all the trouble of LT's aren't worth the hassle when mid length headers have very few issues?
Also can you change the clutch in a m6 without pulling the header out of the way? I know some cars have this issue.
11 Second Club
Joined: Jan 2010
Posts: 1,707
Likes: 13
From: New Orleans, LA
I had pacesetter mids as my first header of choice.. It was night and day over the stock manifolds.. I've since installed long tubes and haven't really been back to the dyno to see how much I gained.. Maybe 10hp max if I had to guess..
TECH Regular
Joined: Sep 2003
Posts: 442
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From: Raleigh, NC
They're decent. I had them on my car years ago.
The biggest drawback to them is the fact that they have individual flanges, rather than the one-piece flange that most other headers have. When you take them on and off a time or two to fix leaks, they end up being tweaked because each primary is "independent" of the others, not having a one-piece flange to hold them all true to shape. The result is eventually leaks that are increasingly difficult to fix.
They were on my car for 7 years or so and perhaps 60k miles. Leaks weren't an issue for the first 4 or 5 years. Ground clearance was just as good as stock. Plug access was better than stock. The car made 290/327 SAE on the dyno back then, with stock engine and stock programming; and later made 358/370 when I added a cam, valvetrain upgrades and a tune.
They're a good choice of header for those who want stock-like ground clearance but still good power gains. They're much better than the SLP or BBK shorties. If someone was very diligent on the installation job and used very high quality exhaust gaskets they could likely avoid the leak issues I had.
The biggest drawback to them is the fact that they have individual flanges, rather than the one-piece flange that most other headers have. When you take them on and off a time or two to fix leaks, they end up being tweaked because each primary is "independent" of the others, not having a one-piece flange to hold them all true to shape. The result is eventually leaks that are increasingly difficult to fix.
They were on my car for 7 years or so and perhaps 60k miles. Leaks weren't an issue for the first 4 or 5 years. Ground clearance was just as good as stock. Plug access was better than stock. The car made 290/327 SAE on the dyno back then, with stock engine and stock programming; and later made 358/370 when I added a cam, valvetrain upgrades and a tune.
They're a good choice of header for those who want stock-like ground clearance but still good power gains. They're much better than the SLP or BBK shorties. If someone was very diligent on the installation job and used very high quality exhaust gaskets they could likely avoid the leak issues I had.
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Verdad Gallardo NewOrleansLT1, Did you notice any low end torque loss when you went to long tubes? Did you feel the increase in HP in the top end over the Mids?
HellTeeOne, Did you run the catless y pipe from Mac? What header gasket would you recommend to prevent leakage? What did you notice with power if and when you went to LT's?
HellTeeOne, Did you run the catless y pipe from Mac? What header gasket would you recommend to prevent leakage? What did you notice with power if and when you went to LT's?
11 Second Club
Joined: Jan 2010
Posts: 1,707
Likes: 13
From: New Orleans, LA
To be honest it's really hard to tell with the butt-o-meter but I would say that I've lost a little down low and gained some up top..
TECH Fanatic
Joined: Aug 2008
Posts: 1,740
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From: Nebraska
Might do a Mac Mid header setup for my 96z28. Any good prices on them anywhere?
good ground clearance
good fitment/ plug access
1 5/8 header helps with low rpm torque, 1 3/4 seems a bit big for my bolt on LT1 which usually sees rpms less than 4000.
Not sure if I would want to keep my air/egr or delete it all and clean up the engine bay a little. No emission checks here in Michigan. I have read that even with Mac Mids that bolt on LT1's can still get 290-300rw.
good ground clearance
good fitment/ plug access
1 5/8 header helps with low rpm torque, 1 3/4 seems a bit big for my bolt on LT1 which usually sees rpms less than 4000.
Not sure if I would want to keep my air/egr or delete it all and clean up the engine bay a little. No emission checks here in Michigan. I have read that even with Mac Mids that bolt on LT1's can still get 290-300rw.
NewOrleansLT1, Did you notice any low end torque loss when you went to long tubes? Did you feel the increase in HP in the top end over the Mids?
HellTeeOne, Did you run the catless y pipe from Mac? What header gasket would you recommend to prevent leakage? What did you notice with power if and when you went to LT's?
HellTeeOne, Did you run the catless y pipe from Mac? What header gasket would you recommend to prevent leakage? What did you notice with power if and when you went to LT's?
TECH Regular
Joined: Sep 2003
Posts: 442
Likes: 3
From: Raleigh, NC
I have had the best luck with Percys header gaskets, the aluminum layered ones. That's what I'm currently running with my LTs. If I had known about them back when I had the shorties, they may have saved me some grief.
I don't have anything quantifiable from when I went from shorties to LTs, as I changed a bunch of other stuff at that same time as well. With any setup making under around 400rwhp, I would imagine the difference between the MACs and the LTs would be less than 10rwhp. At the time I was 'cam only', my tuner insisted that my shorty headers would be "working against me". When the car subsequently made well over 350rw when tuned, he changed his mind on that affair. I do remember the shorties being a night-and-day difference over stock manifolds with the stock engine.
11 Second Club
Joined: Jan 2010
Posts: 1,707
Likes: 13
From: New Orleans, LA
If the primaries on the mids were the same size as the long tubes I would agree.. But the 1 5/8 primary is gonna make more torque down low on a very mild setup.. 1 3/4 primaries are kinda over kill for a bolt on setup BUT it's the way to go because the minute you slap a cam in the car and start revving the engine to the moon the 1 3/4 would do very well in that environment...
TECH Resident
Joined: Jun 2013
Posts: 853
Likes: 32
From: Kernersville, NC
I tried to get a set before going with my Kooks long tubes. They never would make any for the '96/'97.
It's been years since I've checked the MAC site.
I'll say I think the long tubes are a better choice....but just about anything will breathe better than the stock manifolds....and they are a choking point that must be opened up.
It's been years since I've checked the MAC site.
I'll say I think the long tubes are a better choice....but just about anything will breathe better than the stock manifolds....and they are a choking point that must be opened up.
Im pretty sure the 94-95 macs will work with a 96. I want to run there catless connector pipe. New orleans I agree its small block common sense that the 1 5/8 primary will make great low end power for a basically stock lt1. Thats the main reason I want them. And for spark plug access, install from above, easy installation, no y pipe banging the floor board, no ground clearance issues and the list goes on and on, all right im getting winded!
Last edited by 350 groundpounder; Feb 10, 2015 at 12:07 AM.
