Technical Application Notes

High Flow X-Pipe Install

by Michael O'Brien SCMC #075

Here is a job you can do in your garage in under 4 hrs with all the right tools and equipment.  This particular mod will net you a few ponies and will continuously provide you horsepower as you add other modifications.  Opening your exhaust is essential for improved airflow and performance.  X-pipes and H-pipes are available with catalytic converters to allow you to pass emissions and without for road use.  For this installation I installed the Bassani X-pipe for use with factory or shorty headers.  

Other high flow cats are available for full length headers but are not covered in this application note.

Q: Does the x-pipe work with factory headers, mufflers and cat back?

A: You bet!  The x-pipe will fit factory and probably most any after-market cat -back available.  It lined up perfectly with the Mac True-fit cat-back exhaust I have, and before that it previously fit perfect with the stock cats.  It was much easier to install than to remove the old h-pipe since there are no cats at the front of the bassani x-pipe (more room for your hands and tools).  For the money conscious, other vendors provide high flow X and H pipes and provide similar performance and sound.  I have often heard the fit and finish is most important and the Bassani X-pipe was a great fit.

The hi-flow cats are a great mod for the money.  They will increase airflow, have a nice sound, and you can do them yourself!  Be careful buying used stuff, you can always clean up the outside of parts, but the inside may be junk!

Q: Where can I get a new or used set?

A: New high flow catalytics can be purchases at most any aftermarket speed shop.  For club members, see our Vendors page and check for discounts at some dealers.

As for used X/H pipes, it's tough but be patient and you may find a deal.  I bought a bassani x-pipe with only a thousand miles on it for only $300.  Look for other brands too.  I got mine because the previous owner wanted full length headers. That's another very viable option, but headers are very tough to get at in the modular mustang.  I will let someone else do that someday. 

 Here are a few good websites with lots of used parts for sale.

Install Tips

It is not hard to install the x-pipe or an h-pipe.  You need certain tools however and a load of patience. 

For those who have not done work under their car like this, you will absolutely need the following. Others can skip this part.

  • A good floor jack (2 1/2 to 3 ton is preferred) you can do it with out it, but what a pain it would be!
  • Jack stands or tire ramps.  Jack stands are preferred as you can get it up higher (you need it up about a good 1 - 1/2 feet depending on your own girth.  ( I needed a lot of room...too many uh...sodas..ya..)
  • Liquid wrench or similar lubricant (for those of you with southern cars or cars that never see rain, snow, elements you will have a lot easier time then those whose cars see old man winter every year....corrosion is a tough customer ) anyone else may consider giving the local muff shop a few bucks to crack the stock nuts loose on the exhaust pieces with an impact gun (careful what you tell them.  Most states its illegal to remove a working h-pipe, tell them you bought mufflers and headers if you need to.  This is also why its better to do an x-pipe yourself) or you may try a breaker bar over your wrench.
  • A good socket wrench set with a long extension piece
  • Universal joint for the socket (you will not get at the nuts on the headers with out this)
  • I also recommend a chock stop by the back tires, the emergency brake and being in gear is not enough security for me.  Make sure you get the jacks on a secure piece of the frame, out of your working area.

Okay- here we go with the rest.

Once the car is in the air, and you have all the tools, get under there with a flash light and just look around if you have never seen it under there very much before.  Hose down all the nuts and bolts you will remove with liquid wrench or an equivalent lubricating product.

Leave the o2 sensors in the pipe, but disconnect the wires coming out of it at the blue plastic connections. 

The front passenger side is a project to put it nicely with our any nasty words.  I found it easier to go from the side, close to (but not in) the wheel well. The best bet is to get at it the best you can keeping the u-joint as straight as possible. Remove all the nuts that connect your h-pipe to the headers, and to the cat back exhaust pipes which lead to the mufflers.

The last nuts to remove are the hanger nuts in the middle holding it up in the air.  After this, you should be able to shake a little and pull the h-pipe to the ground.  Careful, its heavy and you don't want to get squashed like a grape.  Getting the old pipe down is the hardest part, I found cursing the old h-pipe and those who installed it helped, but what ever works for you.

With the h-pipe out from under the car.  Loosen all the o2 sensors but leave them in their holes.  They each go directly into the same matching spots on your new x-pipe.  I chose to put them in before I put up the x-pipe but its your choice, just don't forget where they go.

With the Bassani x-pipe, you will need to remove the bolts at the muffler end of your factory h-pipe and transfer them to the new x-pipe (mine was used so new hardware may come with yours and you may be able to skip this, I don't know).  This is a pain, but elbow grease and lubrication will get them off.  These go on the same exact way onto the x-pipe.  You should do this before getting the x-pipe under the car.

Once you get everything prepped for installing the x-pipe you will most likely know what's next.  Its pretty easy at this point.  The x-pipe is lighter, gives more room to work, and should line up nicely.  Check for the metal gasket on the passenger front side.  It should still be on the header, but if it came off with you cats, you will need to put in on the new set.  If it breaks, wash your hands and walk to the auto parts store and pretend you are buying a new gasket before you started the project, this way no one will laugh at you when you leave.  As long as its in one piece you should be okay since these gaskets are re-useable.

Hang the x-pipe on the hanger and loosely attach the nuts so it will be off the ground and easy to work with.  Tighten the front nuts first at the headers as they are more important to fit early to ensure a good seal.  Then connect your muffler pipes.  You should always tighten the nuts a little at one end and switch back and forth until tight to bring each side of your connections together for a good seal.  Make sure everything is tight and feel around each seal to make sure there are no gaps.  You wont want to climb back under there when its on the ground and hot.

Reconnect all your o2 sensor clips and you should be all set.  Clean up your mess and fire it up! You will love the sound.  If I have confused you (sometimes I don't make sense) feel free to email me with any questions and I will try to answer them.  Good luck and enjoy!

Michael O'Brien