MAC header concerns

Shotgun28 · 01-26-2001, 12:06 PM

Okay well I just got my new gt40 P heads and from my understanding from calling and emailing companies, the only long tube that will work on the P heads. But is it just my imagination, or is there alot of MAC bashing in here, and I am wondering and nervous to get these, but I already have the long tube h-pipe, and I would rather not replace both the headers and the h-pipe.Could you tell me why they are bad, and what the concerns are when stating they are "crap". Thank you.

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91 LX Convertible Gray on Red B&M Shift improver kit,ASP red alum. underdrive pulleys, Richmond 3.73 gears, 1 5/8 Flowtech long tube Headers and off road h-pipe, Flowmaster 2-chamber cat-back with S.S exhaust, MSD 6A Ignition with coil,Cap and rotor, Taylor Pro wires, K&N 12" conical filter system, Jet stage 2 performance chip and just purchased some GT40P heads, looking at exhaust, Lentech Street Terminator plus on it's way...

Josh91 · 01-26-2001, 12:17 PM

I think there are 2 main reasons for bashing on Mac headers:

1) Individual flanges on the header primary tubes - Flanges may warp from heat over time and cause problems lining up the bolt holes and may cause exhaust leakes
2) HTS coating - This is High Temp Silicone. It is a protective coating that is supposed to protect form corrosion, but is scrapes off easily. I would rather have this than bare steel though.

I think these are valid concerns, but not enough to label them crap. There are A LOT of people that run Mac exhaust. If it sucked that bad, they'd be out of business. There are several local guys that run Mac and have no problems with them, even after a head swap they still line up fine. I am getting Mac LT's soon too. There is a lot of heresay, but I am going off of what I have seen here with my own eyes and that is several people with no problems at all. I say go for it! I would bet they are higher quality than the Flowtech's that you have now.

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1991 Mustang GT - Cobra Intake, FMS 65mm TB, C&L 73mm MAF, GT-40P heads, Crane 2031 cam, Crane 1.7rr, Built AOD, Art Carr 2400 non-lockup converter, Transgo shift kit, BBK chrome cold air, FMS 'P' headers, Pacesetter off-road H, BBK aluminum pulleys, 2-C Flows w/ dumps, 4.10's, Steeda STB, for now...

The Original GT-40P Tech Page

LX XLR8R · 01-26-2001, 01:07 PM

the only people who bash MAC are angry bbk owners who payed more for thier crap..MAC is the $hit..yes the hts coating will scrap of eiser than jetcoating but your not paying for jet coating either..the MACs do get a little harder to put on after thay have goten hot but nothing to hard..they do that so they dont come loose when properaly tightened..people use to cut thier solid flange headers to seperate them back in the day

------------------
1987 black notch(ex 4 banger)
DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one..

LOCASH · 01-26-2001, 02:13 PM

I have them and I am not really impressed. The gaskets they come with are not so great and the bolts are not either. If I had to do it again I would 1) get them shaved down even by a machine shop in case they were bumped around in shipping 2) get some stage 8 fasteners from Summit $31.95 3) get better gaskets (should be number one). I have changed the gaskets and they are still leaking. I have never used anything else so I can't honestly bash them for being crap. I wish I would have just paid more money and bought something better. Bassani?

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86 GT T-tops, AOD, B&M shift kit and hammer shifter, ROH wheels, K&N, Timing,MAC headers, 2.5 off road H, 2.5 American Thunder, 87 spindles, rear disc,SS lines, BBK 1.5, poly bushings, Steeda G-trac and subs, Strut bar.
"DRIVE LIKE YOU STOLE IT!"

Shotgun28 · 01-26-2001, 03:06 PM

Well reagarding something else, I do not have a choice, the MAC longtubes are the only ones that will fit somewhat properly for my GT40-P heads.

------------------
91 LX Convertible Gray on Red B&M Shift improver kit,ASP red alum. underdrive pulleys, Richmond 3.73 gears, 1 5/8 Flowtech long tube Headers and off road h-pipe, Flowmaster 2-chamber cat-back with S.S exhaust, MSD 6A Ignition with coil,Cap and rotor, Taylor Pro wires, K&N 12" conical filter system, Jet stage 2 performance chip and just purchased some GT40P heads, looking at exhaust, Lentech Street Terminator plus on it's way...

stangbang · 01-26-2001, 05:54 PM

I have Mac longtubes and the only bad thing about them is the HTS coating. Mine did not scrape off but it is pretty rusty.I don't drive the car in rain or snow either.

79Stang · 01-27-2001, 09:34 AM

Just bring them to a machine shop before you paint them - get them as flat as possible or suffer later (like me).. Sad when new headers are that far off

01-26-2001, 12:06 PM	#1
Shotgun28 Registered Member Join Date: Sep 2000 Location: New Hope MN USA Posts: 276	MAC header concerns Okay well I just got my new gt40 P heads and from my understanding from calling and emailing companies, the only long tube that will work on the P heads. But is it just my imagination, or is there alot of MAC bashing in here, and I am wondering and nervous to get these, but I already have the long tube h-pipe, and I would rather not replace both the headers and the h-pipe.Could you tell me why they are bad, and what the concerns are when stating they are "crap". Thank you. ------------------ 91 LX Convertible Gray on Red B&M Shift improver kit,ASP red alum. underdrive pulleys, Richmond 3.73 gears, 1 5/8 Flowtech long tube Headers and off road h-pipe, Flowmaster 2-chamber cat-back with S.S exhaust, MSD 6A Ignition with coil,Cap and rotor, Taylor Pro wires, K&N 12" conical filter system, Jet stage 2 performance chip and just purchased some GT40P heads, looking at exhaust, Lentech Street Terminator plus on it's way...

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01-26-2001, 12:17 PM	#2
Josh91 Registered Member Join Date: Nov 1998 Location: Salina, KS Posts: 83	I think there are 2 main reasons for bashing on Mac headers: 1) Individual flanges on the header primary tubes - Flanges may warp from heat over time and cause problems lining up the bolt holes and may cause exhaust leakes 2) HTS coating - This is High Temp Silicone. It is a protective coating that is supposed to protect form corrosion, but is scrapes off easily. I would rather have this than bare steel though. I think these are valid concerns, but not enough to label them crap. There are A LOT of people that run Mac exhaust. If it sucked that bad, they'd be out of business. There are several local guys that run Mac and have no problems with them, even after a head swap they still line up fine. I am getting Mac LT's soon too. There is a lot of heresay, but I am going off of what I have seen here with my own eyes and that is several people with no problems at all. I say go for it! I would bet they are higher quality than the Flowtech's that you have now. ------------------ 1991 Mustang GT - Cobra Intake, FMS 65mm TB, C&L 73mm MAF, GT-40P heads, Crane 2031 cam, Crane 1.7rr, Built AOD, Art Carr 2400 non-lockup converter, Transgo shift kit, BBK chrome cold air, FMS 'P' headers, Pacesetter off-road H, BBK aluminum pulleys, 2-C Flows w/ dumps, 4.10's, Steeda STB, for now... The Original GT-40P Tech Page

01-26-2001, 01:07 PM	#3
LX XLR8R Dirk Diggler Join Date: Feb 1999 Location: SLOATSBURG, NY Posts: 1,931	the only people who bash MAC are angry bbk owners who payed more for thier crap..MAC is the $hit..yes the hts coating will scrap of eiser than jetcoating but your not paying for jet coating either..the MACs do get a little harder to put on after thay have goten hot but nothing to hard..they do that so they dont come loose when properaly tightened..people use to cut thier solid flange headers to seperate them back in the day ------------------ 1987 black notch(ex 4 banger) DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one..

01-26-2001, 02:13 PM	#4
LOCASH Registered Member Join Date: Oct 2000 Location: Santa Lucia di Budoia, Italy Posts: 217	I have them and I am not really impressed. The gaskets they come with are not so great and the bolts are not either. If I had to do it again I would 1) get them shaved down even by a machine shop in case they were bumped around in shipping 2) get some stage 8 fasteners from Summit $31.95 3) get better gaskets (should be number one). I have changed the gaskets and they are still leaking. I have never used anything else so I can't honestly bash them for being crap. I wish I would have just paid more money and bought something better. Bassani? ------------------ 86 GT T-tops, AOD, B&M shift kit and hammer shifter, ROH wheels, K&N, Timing,MAC headers, 2.5 off road H, 2.5 American Thunder, 87 spindles, rear disc,SS lines, BBK 1.5, poly bushings, Steeda G-trac and subs, Strut bar. "DRIVE LIKE YOU STOLE IT!"

01-26-2001, 03:06 PM	#5
Shotgun28 Registered Member Join Date: Sep 2000 Location: New Hope MN USA Posts: 276	Well reagarding something else, I do not have a choice, the MAC longtubes are the only ones that will fit somewhat properly for my GT40-P heads. ------------------ 91 LX Convertible Gray on Red B&M Shift improver kit,ASP red alum. underdrive pulleys, Richmond 3.73 gears, 1 5/8 Flowtech long tube Headers and off road h-pipe, Flowmaster 2-chamber cat-back with S.S exhaust, MSD 6A Ignition with coil,Cap and rotor, Taylor Pro wires, K&N 12" conical filter system, Jet stage 2 performance chip and just purchased some GT40P heads, looking at exhaust, Lentech Street Terminator plus on it's way...

01-26-2001, 05:54 PM	#6
stangbang Registered Member Join Date: Oct 1999 Location: brunswick,ohio Posts: 135	I have Mac longtubes and the only bad thing about them is the HTS coating. Mine did not scrape off but it is pretty rusty.I don't drive the car in rain or snow either.

01-27-2001, 09:34 AM	#7
79Stang The Stang Gang Join Date: Jan 1999 Location: St. Petersburg Posts: 63	Just bring them to a machine shop before you paint them - get them as flat as possible or suffer later (like me).. Sad when new headers are that far off