HELP!!! MAC o/r H-pipe sounds like crap...

elite130

Member
Dec 7, 2005
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Denver, CO
Last night I installed my MAC off-road H-pipe w/ MIL Eliminators. When I took the car out last night, the car sounded like crap (IMHO). I have a MAGNAFLOW cat-back BTW. It sounds good down low, but once I hit about 2500RPMs thru the rest of the RPM's, it sounds like a freaking machine gun going off. Really loud and poppy. I have heard about this sound with the Magnapacks, but not with the magnaflows. Did I do something wrong? I installed a new Ford gasket between the passenger-side and did NOT use the MAC provided gasket. Should I use the MAC gasket with the new Ford gasket, or only use the MAC gasket? Would that change anything? Help me! I am very disappointed with the sound. Everyone told me it sounded deep and awesome, I am getting the direct opposite.
 
I installed the MAC o/r h-pipe with Flowmaster Delta 40's. If I bog the engine under a load, it sounds really bad. Sounds like a big red-neck truck with 5-inch diameter tailpipes! Now, off idle up to around 2500 rpms it's sounds good. And at WFO in higher rpms it sounds totally freakin awesome!!!

I have just learned to drive the car differently. In fact, I kindof had to because it is so freakin loud now. I got 3 bad looks from the cops in the first week I put it on, so I just take it easy now.
 
Weird, I recently put on a MAC o/r H with my MAC longtubes and Flow 40 weld ins and I thought it sounded great (except for my longtubes rattling. Maybe you have some kind of exhaust leak. For some reason, I have always had a leak ever since I touched the exhaust. Check all your connections again and make sure its all tight. If its new, the sound might change, give it some time. Mine was used.
 
Before you get too worked up, have someone else drive you car around so you can hear it from outside the car. When I first installed my prochamber with the flowpaths it took me a little time to get used to it. I love it a year later and I believe the sound does improve some over time. I'm not sure how DEEP the magnaflows are going to be...you'd get a deeper sound with mac flowpaths or flowmasters. However, it still shouldn't sound like a machine gun...check for exhaust leaks if you have any performance issues or it doesn't grow on you any.
 
Man that sounds like exactly the problem I had with my old system, but I had O/R with Magnapacks. It would make this really annoying tin metal machine gun noise after 3k RPM's up until about 5k, then after that it sounded good again. I then switched to the Magnaflow catback, and NO longer have any of that. It is DEEP and sounds the same throughout the RPM range. No popping, tin metal, or machine gun noise what so ever. Are you positive you have the Magnaflows?? For some reason I think you have the Packs. I just dont see how it could sound like that with the regular Magnaflow catback.

Do your pipes look like this:

15673.jpg


Or like this:

13sa3.jpg
 
They are the Regular Magnaflows, not the Magnapacks. I don't know what to do. I'm going to make sure that I have no leaks and I may try using MAC's passenger-side gasket w/ the Ford gasket for the connection b/t the exhaust manifold and h-pipe. Other than that, I don't know what else it could be.
 
The sound you are most likely hearing is an exhaust leak. I had the same problem when I first installed mine. They like to leak around the passenger side exhaust manifold and the couplers where the H-Pipe connects to the cat-back. You just have to just keep tweaking it, adjusting and tightening all the pipes until you get rid of all leaks, maybe even silicone some places if you have to.
 
This is vertually the same post I was going to make. Only I installed a BBK offroad X-pipe and I also have the Magnaflow cat back. I'm not sure if I have a leak, or it's inherant with the BBk off road x-pipe. I tried listening for a leak by plugging each tailpipe and listening. no leak. Probably have to plug both tailpipes at once. At idle or light throttle it sounds awsome. Wide open throttle its :nice: :nice: :nice: :nice:
But at moderate throttle it sounds horable.:shrug: I know the BBK x-pipe has a poor rep with chambered mufflers, but thought it was ok with Magnaflows and other straight through mufflers.
 
elite130 said:
Last night I installed my MAC off-road H-pipe w/ MIL Eliminators. When I took the car out last night, the car sounded like crap (IMHO). I have a MAGNAFLOW cat-back BTW. It sounds good down low, but once I hit about 2500RPMs thru the rest of the RPM's, it sounds like a freaking machine gun going off. Really loud and poppy. I have heard about this sound with the Magnapacks, but not with the magnaflows. Did I do something wrong? I installed a new Ford gasket between the passenger-side and did NOT use the MAC provided gasket. Should I use the MAC gasket with the new Ford gasket, or only use the MAC gasket? Would that change anything? Help me! I am very disappointed with the sound. Everyone told me it sounded deep and awesome, I am getting the direct opposite.

I ran into the same thing with my 04 GT. That popping you are hearing is because of the o/r pipe. That machine gun noise you hear will not go away over time with an o/r pipe. You have a couple of choices. Weld in a set of high flow cats into the o/r, buy a catted h-pipe, or switch mufflers. I ended up installing my oem midpipe back in.

Here is a vid of my car in first gear with Magnaflow mufflers and a mac o/r H pipe.

Magnaflows/Mac o/r H

Hope this helps.
 
id wait alittle while before u change your mind about it.
i have magnapacks with o/r h and at first it was a much different sound from the usual flowmaster mustang. but now i really like the sound.
 
Scott04GT said:
I ran into the same thing with my 04 GT. That popping you are hearing is because of the o/r pipe. That machine gun noise you hear will not go away over time with an o/r pipe. You have a couple of choices. Weld in a set of high flow cats into the o/r, buy a catted h-pipe, or switch mufflers. I ended up installing my oem midpipe back in.

Here is a vid of my car in first gear with Magnaflow mufflers and a mac o/r H pipe.

Magnaflows/Mac o/r H

Hope this helps.
I love the way your car soundes in that vid!!:nice: :nice:
If mine sounds like that from the outside, I'd be thrilled. That's the sound I was going for. Maybe it just sounds wierd inside the car? Actually I find after about 10 minutes it sounds, a lot quiter on mine. The Magnaflows seem to need to heat up before they sound right, even with the stock mid pipe.
 
MaxedGT said:
I love the way your car soundes in that vid!!:nice: :nice:
If mine sounds like that from the outside, I'd be thrilled. That's the sound I was going for. Maybe it just sounds wierd inside the car? Actually I find after about 10 minutes it sounds, a lot quiter on mine. The Magnaflows seem to need to heat up before they sound right, even with the stock mid pipe.

If you want your car to sound like that, they throw on a o/r h-pipe and you will be there.

Its hard to tell, but that machine gun popping is very loud, inside and outside the car. In person, its sound like a redneck Chevy truck with a hole in the muffler.

I commute 30 miles each way to work everyday, so I figured that I would give them some time to break in. But after about a week or so, it was still doing that crap, so I pulled off the o/r off.