View Full Version : ?'s on installing h pipe and catback

03-22-2005, 11:02 AM
I finally got my Mac H pipe and Flow Amer. Thunder system here and now it's time to install them. Now I've done several searches and found out some very good/helpful information but I still have a few questions.
1. Since I'm going to switch out both the same day, will I have to jack to car up from both ends and support it with jack stands or ramps (4 tires off the ground at the same time) or will I do one end at a time?
2. When removing the stock h and catback where do I start? H or catback?
3. Will I have to cut anything or can I just unbolt and slide the stock parts off :shrug:
What other tips do you guys have for me to make this as painless as possible?

03-22-2005, 11:47 AM
You're going to want the whole car up off the ground, whether it be with jack-stands or ramps so you can get to everything easily. As far as the order, I'd loosen up the cat back first, then work you way up to the h pipe. There is a hanger near the 'h' in the pipe that can be a little tricky to get loose as well. Everything is bolted up, so you shouldn't have to cut anything to get it out. A word to the wise - be gentle when your taking the nuts on the exhaust manifold loose. Use a good penetrating lubricant of some kind....I used a cheater bar instead, and the whole stud, with most of the surround threads, came out with it. Trust me that was slightly less than fun. Aside from that the Mustangs in general are the easiest exhaust setup I've ever worked with. Best of luck!:thumbsup:

03-22-2005, 04:29 PM
I have to agree and the bolts on the exhaust manifold are the hardest to get to and remove. lots of heat and not mush room.

03-22-2005, 05:29 PM
Looking at the h pipe and it's in 3 pieces. I was gonna put it together but it didn't come with any directions and I thought I'd ask before attempting to put it together. It came with 1 gasket and what looks like a coupling (for lack of a better word). Where does the gasket go and what do I do with the "coupling".


03-22-2005, 09:05 PM
Your factory headers have a flat side and a ball side. I believe the passenger side is flat while the driver side has a ball and socket to seal the exhaust. I would just mount the two pieces that go to the headers first and then bolt up the third piece leaving everything loos for alignment later. The paper gasket is for the flat side while the coupling is for the ball and socket side.

Your 99 exhaust is a sinch to remove so go ahead and take it out. Replace all of the stock stuff with the aftermarket catback. I would mount everything loosely till everything is ready to tighten down.

Then starting with the front of the vehicle, align and tighten everything so that nothing touches the body of the car and you have everything adjusted so that it gives you as much ground clearance as possible.

You may have to "tweak" the sytem a little to make sure you do not have any rattles with the exhaust touching anything. Go back a week later or so and retighten everything just to make sure.

Enjoy your new tunes! :)

03-23-2005, 09:52 PM
Damn, that factory mid pipe was a b*&^$ to get off. The passenger side took me about 30 minutes just to get the left nut off and then the driver side gave me a problem too when the whole screw on the left came off with the mid pipe. Damn, and someone told me this was a 2-3 hour job. Yeah, right! Well tomorrow all I have to do is go buy some extra nuts and bolts to bolt up the cat back and straighten/tighten everything up. I can wait to start her up.

03-24-2005, 12:11 PM
Finally finished:headbang::banana::clapping:. Well almost, just have to plug up the MIL eliminators, hopefully they should be getting here later today. Do the mil's hook up to the front 2 sensors or the rear 2? I have to say that the install wasn't difficult but it was tricky. Overall, I would definately do it again myself instead of taking it to a muffler shop. Now, in 6 months i'll be taking off the h pipe and putting the oe one back on for emissions testing. Yey!

03-25-2005, 10:52 AM
Congrats on your install. Depending on where you are you may not have to switch back. The mil elim tricks the computer to think everything still there.
MIL elim's go after the cat or the back set of O2 sensors.