My notes on installing a Bassani X-pipe with Cats and a Bassani Cat-Back System.....

***************
Based on my limited, one car, experience for a 99 Cobra, installing a
 4699-3 x-pipe with cats, and 4699C-5 cat-back system..

 These two kits can be installed one at a time or both at the same time. You will have to
 have the entire car up on jack stands or on a lift to do both at once.

 X-pipe with cats

 1. Be prepared for the driver's side pipe to not fit perfectly at the exhaust manifold. Suggest
 you get a spacer ring from Bassani before you start the installation just in case you need it.
 Suggest starting with a cold engine.

 2. Disconnect right front and both rear O2 sensors before unbolting the stock x-pipe. Unbolt
 both the rear flanges, and then the passenger side manifold flange nuts, then the driver's
 side maniflold flange nuts, then drop the pipe down enough to gain access to the driver's
 side O2 sensor plug, unplug it, and then lower the stock x-pipe. You will need a 15mm deep
 socket and 18" extension for the manifold nuts, and 9/16" deep socket and ratchet for the
 rear flanges.

 Find the right side manifold gasket, check it for damage, and place it back into position over
 the stud bolts.

 3. Move the O2 sensors over to the new x-pipe one at a time before hanging the new
 x-pipe. Use a 7/8" open end or 22 mm. Use a little of the Bassani-supplied antiseize on the
 threads and put them in the same locations that there were in on the stock pipe. Don't get
 any antiseize on the sensing element itself. Snug them, don't overtighten.

 3. Trial fit the new Bassani x-pipe, making sure not to damage the right side manifold gasket,
 which can be re-used if you don't damage it. Check to make sure the driver's side pipe fits
 the manifold and that you can get the flange over the studs without prying the pipe over.

 4. If everything looks like it will fit, drop the pipe an inch or so and plug the driver's side
 sensor back in before raising the pipe into final position and starting the nuts on the manifold
 studs. Use the spacer ring if you need to. Start the nuts on all both manifold flanges, making
 sure the gasket is installed properly on the passenger side.

 5. Use the new Bassani 3/8 bolts on the rear flanges, use a little antiseize on the threads,
 snug the flanges to the mufflers. Make sure the flanges are square and tighten them equally
 on both sides.

 6. Start the car up and let it idle. Check for leaks by feeling around the flanges before they
 get too hot. Fix any leaks. I had to cut and weld mine to fix an alignment problem, but this is
 rare, I hope.

 Cat-Back System

 Installation can be done by raising only the rear of the car.

 1. Make sure you have two 2-1/2" pipe clamps, one for each side, when you unpack the box,
 before you start. I was short one clamp and had to go get one.

 2. I first sprayed some silicone spray on the rubber hangers that seemed to make it easier to
 get them off the stock pipe hangers. They can be forced off by hand if you support the
 pipes and unload the hangers.

 3. You will have to remove the two rear hangers near the bumper with a 10 mm socket and
 extension before the stock pipes can be dropped down.

 4. Check for adequate floor pan clearance on the right side muffler, inlet end. The pipe from
 the cat-back flange to the muffler inlet was a little short (1/4") on mine and I may have to
 put a spacer ring or two in the joint to get adequate clearance, whatever that is. My guess,
 about 1/4" minimum is what is needed, to be confirmed by Bassani.

Hope this helps.
Joe Lynch