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Report on Bassani "Off-Road" X-pipe setup for my 2001 Z06

(This was recently posted on the C5 Registry listserve and I received several questions which prompted some revisions and updates included here.)

1. Description, quality, fit & finish, price

Bassani makes an "off road" X-pipe setup that is particularly handy for those who want to be able to go back and forth to stock if need be. It actually consists of two Bassani pieces, the "front" piece, part # C501-2 which replaces the part of the stock pipes with the 4 cats, and the "rear" piece, part #5797X. Each piece contains an "X-pipe" section welded in. Actually, each piece was designed to be used separately if you want to cut your stock pipes in the middle. But by combining the two, your stock pipes remain intact and can be bolted back on.

The two pieces slip together in the middle and clamp tight, and the two piece assembly bolts to the exhaust manifold in front and the muffler pipes in back. This way, you jack up the car, remove 8 bolts and 6 nuts, replace the stock pipe with the Bassani pipe, replace 8 bolts and 6 nuts, and go. (See details below.)

I was impressed with the quality and fit of the Bassani parts. All the mounting fittings and hangers were in the right places, flanges are thick and flat. Everything fit just right (except for a slight mis-alignment of the muffler pipe flanges - see below). You couldn't ask for a more quality setup.

The pipes themselves are made from heavy gauge material which should improve service life. After extended use, exhaust pipes become corroded by the sulfuric acid produced when the sulfur in gasoline burns. Exhaust heat just speeds up this process. Pipes made from thin material tend to quickly "rust" through, although it is not really rust, the pipe is actually eaten away by the sulfuric acid. The Bassani pipes should resist such corrosion longer than most.

Bassani pipes are sold through its dealer network. There is a "list" price, but most dealers discount that price. I paid $310 for the front piece and $235 for the rear plus sales tax. This price included shipping. It seems reasonable considering the $1,000 to $1,200 price charged by the Corsa/Borla-type muffler firms. Shop around, you may find an even better price.

2. Initial fit problem solved

Earlier I reported that the original "front" piece that Bassani sent did not fit my Z06. After a telephone call, Sheldon at Bassani asked me to make a measurement on the pipes. It turned out that even though the piece had the correct part number engraved on it, it was not the correct part. Apparently the piece had been mis-labeled during manufacture, and no one caught the error. This would be easy to miss, as the two parts (LS6, LS1) look the same and are less than an inch different. After profuse apologies, Bassani immediately sent me the correct part. I must say their people were great.

3. Weight vs. stock

Stock pipes with cats: 42 Lbs.
Bassani 2-piece assembly: 27 Lbs.
Weight saving: 15 Lbs.

Neat, eh? Removing weight is like adding horsepower.

4. Installation details

As I mentioned above, installing this setup consists of removing and replacing 8 bolts and 6 nuts. However, there are a few details that might be helpful.

Start by assembling the two Bassani parts. Before mating, loosely place one of the clamps that Bassani supplies over each of the junctions. Bassani also supplies a tube of anti-seize compound. I used a thin coat on the pipe ends before slipping them together to ease adjustment of the final length after the parts were in place on the car.

The installation basically involves lifting the car onto jack stands, supporting the middle of the stock pipes with a jack just behind the large cats, and removing the 8 bolts and 6 nuts. The stock piece is now loose and can be slid down and to the rear until it is free of the manifold studs. Then lower the jack. Balance the Bassani pipes on the jack, jack it up into the right place while sliding the pipes forward onto the manifold studs, and then replace and snug up the 8 bolts and 6 nuts. Slowly tighten the 6 manifold nuts first with the other bolts very loose. Tighten the 6 nuts evenly a little at a time to slowly pull the pipes up to the manifold. After the manifold nuts are tight, do the final tightening of the other bolts. (Don't forget to use anti-seize compound.) Before final tightening, adjust the length of the Bassani assembly by sliding the two pieces together or apart so the muffler pipe flanges are in the right place. Then torque everything to the torque specification in the service manual.

The anti-seize compound comes in handy at many places. The six self locking nuts that attach the pipes to the exhaust manifold require excessive force to loosen and tighten. The force required is so great that sometimes the exhaust manifold studs bend! After removing the nuts several times (trying different pipes), my studs were bent! Fortunately, the studs can be removed from the exhaust manifold and replaced with new studs (see Chevy part numbers below). Use anti-seize compound generously on the studs and nut threads when replacing and tightening these nuts. The anti-seize compound reduces the force required. To remove the manifold studs you need a "thin" 15mm open end wrench. I don't have one, and some of the old studs would not come out, so I reused them.

To use these "off road" pipes, you must remove the rear pair of oxygen sensors and replace them with "oxygen sensor simulators" (available from several vendors, mine came from Breathless). But Bassani dutifully welded the fittings for the rear oxygen sensors to the (front) pipes. So you must plug these holes. It is a metric 18mm x 1.5 plug, unavailable at any hardware supplier. Fortunately, Chevy has a plug; the part number is listed below. Use anti-seize compound.

On the stock pipes, the rear flange is threaded to accept the (metric) bolts that attach the muffler pipes. The Bassani part is not threaded. I purchased four comparable size bolts and self-locking nuts from a local hardware store (not in a metric size, though). The fit of the flange on the rear Bassani pipes and the muffler pipes was a little off, but pulled together when I tightened the bolts/nuts. The two pipes flexed a little to fit. So far so good. Use anti-seize compound.

Finally, when everything is bolted up and you have adjusted the length of the Bassani 2-piece assembly, position and tighten the clamps Bassani supplies to keep the two pieces fixed together. For my car, the "shortest" length was the best fit. Use anti-seize compound on the clamp bolt and nut. (For a really neat job, have the two pieces welded together after adjusting the length.)

5. Additional note on "Oxygen Sensor Simulators"

On my 2001 there are four oxygen sensors, or two pairs, the "front" pair which screw into the two exhaust manifolds, and the "rear" pair which screw into the pipes just behind the large cats. It's this second "rear" pair you need to simulate if you remove the cats. Otherwise you will get "cats not working" trouble codes.

The front pair are used in "closed loop" by the computer to keep the mixture at stoichiometric, that is, at equal amounts of fuel and oxygen. The front pair are essential for the correct function of the engine. On the other hand, as far as I can tell, the rear pair are only there to be sure your cats are working correctly, and to give you a bunch of trouble codes if they aren't.

The fittings for the front pair of oxygen sensors are in the exhaust manifolds and not of interest to you. The rear pair of oxygen sensors holes are in the *front* Bassani "off-road" X-pipe part. Why they put these fittings onto the pipes puzzles me, because the computer would go wild if you installed the rear oxygen sensors there with no cats. There are no fittings for oxygen sensors in the rear Bassani pipes.

6. Additional Note on "Fit"

Above I mentioned that the rear X-pipe to muffler flange fit was a "little off". In a week of driving the car, I have noticed a "tic-tic-tic" under moderate acceleration and somewhat more noise that just after installation. I suspect that there may be one or more exhaust leaks that I need to fix, possibly at the "a little off" fitting, but work has kept me out from under the car. I'll update this report when I find out what's going on.

7. Additional parts I needed

The first three parts are available from your local Chevy dealer. My dealer had to order all three (delivery in about 4-5 days). The price is a little high, so only replace the studs and nuts if they are damaged. Take one of the muffler pipe bolts to a hardware store and get four equivalent-sized American bolts and self locking nuts to attach the muffler pipes.

Part Part # Quantity Price ea.
------------------------ --------- ------ ---------
Manifold stud 012562640 6 $3.55
Self-locking nut 010255857 6 $1.80
Oxygen sensor hole plug 025509274 2 $3.33
Bolts & nuts for
muffler pipes N/A 4 ea. ~$.50

8. Exhaust sound

The improvement in the exhaust sound was remarkable. At idle and below about 2,000 rpm there is almost no difference. I can cruse along at 1,800 rpm at 75 mph and listen to the stereo. At this speed, wind noise is the largest distraction. This is in line with my observation that the un-muffled Mosler prototype with stock Corvette engine at Daytona was very quiet at idle (and not that loud at full song).

Above about 2,200 rpm at more than 1/4 throttle the engine begins to emit a real **rrraaaaappp**. It is *not* like the classic V8 rumble. Apparently the firing order change raises the frequency of the emitted sound in a manner that is very pleasing to me, much like the old V12 Ferraris. At WOT it is a **much** louder RRRAAAAAPPP!

This raises another issue. Apparently the stock Z06 *mufflers* really don't "muffle" that much. (Its probably the same with the stock C5 mufflers.) It appears that a substantial part of the Corvette "muffling" job is done by the cats. This may explain why Borla/Corsa is unable to produce any more HP - there isn't that much restriction in the stock mufflers to start with. IMHO, replacing the cats with the Bassani setup (~$550) makes it unnecessary to spend $1.200 on the Borla/Corsa solution, and I believe (but can't prove yet) that you do get more HP.

9. Performance

This is a tough question. In theory the Bassani pipes should yield 15-18 hp. That's in theory. GM said that loosing just the "pup" cats yielded 5+ HP. These pipes have been on my car less than a day, so I'm not sure yet. The engine seems to run better and have somewhat more power, but that RRRAAAAAPPP makes it sound so good that it would be easy to fool oneself. I don't have a dyno, so I don't have any hard data to give you. After a couple weeks when the engine has a chance to "relearn" the increased flow characteristics, I will update this report.

P.S. I am not associated with Bassani in any way and own no stock in Bassani. I'm just a satisfied user of their parts.

Keep waving!
Jim Green
[email protected]
2001 Z06, "Arrest Me" Red/Modified Red, Halltech TRIC+MAG+throtle body heater bypass, lowered 1", Bassani off-road X-pipe, Doug Rippie roll/harness bar, 6-point harness, braided stainless break lines, CAGS eliminator, stay tuned, more to come.
 

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Wow, Thanks for the info ! I may do just what you did !
I just decided a few days ago to install the short headers so I did
not need to worry about the welding of L/T headers and the possibility of returning my Z to stock in the future. This seems to
take care of those concerns,

Thanks !

:D

2Charmed
 

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Based on the comments about corrosion, I am slightly confused about the material.. Is it stainless? 304 or another alloy?

The Bassani homepage is down, so no info there..
 

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Jim:

Very nice, well written article. Thanks for the great info!

Zippy :z: :z:
 

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I ordered the parts for this set up today,
we'll see how it goes!
:D

2Charmed
 

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Jim,

Will be there in a month or so.

Really appreciate your post...

2k :cool:
 

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Jim, Great post.. I have a question for you.... I have the Corsa Indy Pro's, I also have the Bassani X pipe on the car now.

What would you say, how loud would it be if I put the front section on? I would think that the rear pipe would be the same as you put on.

I also have the B&B Triflow Shorty Headers on.

Also any new input on the sound and power now that you have had it on for a while.

Ernie
 

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I don't know about putting the front part on, how it will fit with
your current set up. I do have both Bassani parts on and the
stock Ti exhaust with B&B shorties. It is louder than stock and is
certainly more powerful. I don't have any numbers though.
It is somewhat smelly and the back of the car gets a lot of carbon
on it. Overall I am glad I did it and am looking into a head and cam
package now.

Good luck,

2Charmed
 

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I unscrewed the O2 sensors from the stock pipe. I assume I also need to separate the casing from the screws that go into the stock pipe in order to fit the O2 simulators. How do you separate the casing to reveal the plug?

Thanks in advance!
 

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where can i order this
 

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West Coast Corvette


2Charmed
 

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Bassani Off-road X-Pipe

Is anybody running this setup on an '02? I contacted Bassani and was told they were unsure if this combo would work on an '02 since the pup cats were no longer being used. :-?

Chris
 

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The set up should work for the 02' The pup cats just took up space that is now just additional pipe. The space is still the same,
as the manifolds and are still the same dimensions.

2charmed
 

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2charmed said:
The set up should work for the 02' The pup cats just took up space that is now just additional pipe. The space is still the same,
as the manifolds and are still the same dimensions.

2charmed
Thanks for the info...... I thought this was the case. :cheers:

Chris
 

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mine was $350 or so $545 most have hiflow cats
 
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