rominl

iTrader: (4)

ah thanks for the explanation hameed. it's good that it stays relatively quiet inside the car. that's a must for cars like ours.

skperformance

iTrader: (6)

Very nice , but it does sound much better in person.
It has a tinny sound to the end of the notes that i did not notice before but it is probably just the camcorder picking up a frequency.

lexforlife

iTrader: (7)

hameed

your car sounds mean as hell..it emits a dont mess with me tone really nice


i wonder how this would sound with the hks exaust

GS300Rich

Man Hameed that exhaust sounds great. When I watched my eyes went Makes me wish I had a 400

Hameed

Thanks GSV8! I am hoping for at least 10 RWHP gain. The K&N intake should have (at least according to the dyno sheets from K&N) added another 9 RWHP, so your guess is close - hopefully 260 RWHP total now.

I first need to buy the Apexi SAFC II, tune the car and then dyno after that.
Thanks LexT!

Hey TAMR_GUS98, the shop made new flanges that were welded to the new pipes and then bolted to the cats up front and to the L-tuned mufflers at the rear.

You should definitely do this mod - it is a blast to hear that sound on WOT.

Hameed

Thanks KevinGS! You ought to do this mod too!

This won't have any adverse effects on passing a smog test simply because I did not touch the cats up front.

The center mid section that I thought was a cat was actually a resonator and NOT a cat.

I will be getting my car tested this weekend as my plate sticker is up for renewal.

Thanks Sharad! Yes it definitely does sound better in person.

The camcorder does make it sound tinny - I don't think the camcorder captured the actual sound accurately enough. It especially sounds tinny when revving at a standstill.

Hameed

Thanks Ed! I think if you did this mod with your HKS muffler, you car will sound even more meaner than mine! Go for it!

Just get rid of your 300 and get a 400!

JBrady

Very nice!

Quality work, quality result. GREAT sound.

Curious on the center resonator. Seems that CA equiped GS400s "may" have a center cat and some Canada cars "seemed" to report the same. Was yours originally a Canada car or a 49 state car?

SBMGS4

Awesome stuff Hameed...

Thanks for sharing and continuing to foster new ideas!!

Hameed

Thanks John! You realize your help had a lot to do with my feeling comfortable about this mod. Do you see any bottlenecks with my setup?

My car is originally a Canadian model spec car. I was also under the impression that center resonator was a cat. However after the tech removed it, he confirmed "visually" that it was just a resonator..........

Hameed

This article was one of the pieces of research that inspired me to do this mod http://www.vetteweb.com/tech/0307vet_xpipe/index.html


It is about the X-pipe install on a C5 Corvette



I'll get right to the point--recently I was able to buy a used C5 coupe to be my daily driver. I actually found a three-year-old C5 that was absolutely stock. The wheels were standard silver finish, it still had an AC Delco paper element air filter, and it didn't even have custom tips on its original equipment exhaust system. That's right, the funky little black tips were still there, gracing the factory's meek and mild sounding pipes and mufflers.
A few people may like the sound of a stock C5 exhaust. I haven't met one yet, but that doesn't mean they're not out there. Personally, I think non-Z06 C5s should sound a little more muscular; Z06s don't need a lot of help in that--or any other--department. I wasn't real excited about my C5 sounding almost as sedate as the late-model Cadillac De Ville owned and occasionally driven by the old folks down the street.



On the other hand, I didn't want my everyday ride to be too loud, or to suffer the dreaded interior resonance syndrome that's so commonplace on some cars with modified or custom exhausts. What to do...

I wanted to do something different; something we haven't done previously. That meant not just the de rigueur cat-backs. Almost every company involved in the C5 exhaust aftermarket is building systems from stainless steel Continued on Page 52 couple are now going way-high-bucks with titanium, a la the Z06. Titanium is excessive for my needs and for this car. After all, it's an automatic, it's a coupe, and it's a commuter--the 12-18 pound weight savings doesn't matter on this sort of car. All I wanted was something that looks good, sounds muscular, and might produce a few more ponies.

Anything forward of the catalytic converters is considered emissions related by the EPA types. I don't want headers on this car and I don't want the hassles when it comes time for smog inspections. That leaves trying an "X" type crossover pipe, which replaces the behind-the-cats "H" style factory crossover, in addition to some sort of cat-back system.

I know of three manufacturers of Corvette exhaust systems that also offer X crossover pipes for C5s; there may be others. All three of these companies make very high-quality products. The systems from all three are stainless steel and one also offers at least one system in titanium. One company is in the Midwest, and we've done C5 exhaust articles with them. The other two are located within a 50-mile radius of our headquarters here in Southern California. I made my decision based on convenience. One of them--MagnaFlow--has an in-house tech center with several installation bays and a Dynojet chassis dynamometer for testing purposes, and the other does not.

I wanted to find out exactly what difference, if any, an X crossover would make. Thus our agenda was to take baseline noise level readings on the C5 then establish "stock" horsepower and torque output on MagnaFlow's Dynojet. Then we'd install the Muffler Assembly (PN 15713), test drive the car and take noise level readings, followed by more pulls on the dyno. Finally, the Tech Center crew would install the X pipe (PN 15437) followed by another drive test, more noise measurements, and final dyno tests. The X pipe and Muffler Assembly are available as a set under PN 15660.

Crossover pipes on dual exhaust systems are supposed to balance and smooth out exhaust pulses between the two sides of the system. Theoretically, the crossover should also give a slight improvement on exhaust gas scavenging, which should offer some modest gains in power output. On C5s, the intermediate pipes (forward of the rear axle and aft of the catalytic converters) have a crossover, a straight section of pipe running perpendicular between and connected to the intermediate pipes. Many people refer to this as an H pipe or an H crossover.

An H section is inexpensive to mass produce. It's better than no crossover or balance tube whatsoever, but it is fairly inefficient. Exhaust gases want to follow the path of least resistance--that's why smooth mandrel bends produce better power than crimped and uneven (i.e. the corner muffler shop) bends on exhaust systems. Unless forced, exhaust gases are not going to make the hard 90-degree turns you see on an H pipe. An H pipe will offer some benefit, but not a lot.

An X section, with gentle beds and an open center chamber, offers substantially better balancing or equalizing of the exhaust gas pulses than are possible with an H crossover. Ergo, an X crossover should, with no other changes, offer enhanced power production. It should also eliminate the burbling and popping on deceleration that's not especially uncommon on aftermarket C5 cat-backs. We'll see.

Mother Nature put a crimp in our plans with a multi-day downpour that straddled our scheduled installation. The inclement weather precluded our intended exhaust noise measurements (wet roads would severely skew the interior sound levels) and also meant that we'd have to cut way back on the "vigorous" driving. We weren't going to let a little bit of liquid sunshine interfere with things since MagnaFlow's Tech Center and dyno are well protected from the elements. And we had a semi-adequate fallback plan for the sound level measurements.

One year ago we ran a series of tests on fellow Primedia staffer Randy Fish's C5 coupe, which is essentially a twin, albeit one model year older, to my "new" Corvette--a base interior and automatic with 3.15:1 gears coupe. Both cars are even shod with OEM run-flats. While no two cars are ever exactly the same, this pair ought to be close enough for comparative purposes. The after part of the sound measurements would be done at our offices (same place we'd tested Randy's car last year) and the only thing we'd be unable to measure would be what effect the X pipe would have on the noise levels from the MagnaFlow cat-backs. I gotta admit that I was a little apprehensive about how loud it might be, thanks to their naming the system "Wide Open" and touting the mufflers as having no baffles, no chambers, no louvers, and no restrictions.

I'm not going to rehash a C5 cat-back installation. The MagnaFlow system fit very well and is a gorgeous piece of work, with mirror-polished mufflers, outlets and quad tips. The guys in the Tech Center offered a suggestion that's simple and good to remember. Unbolt the rear stabilizer bar from the differential carrier and swing it down and out of the way before trying to remove the old pipes and mufflers; also temporarily remove the passenger side gas tank shield. The old system will come out a lot easier and your new setup will slip into place easier, too. Of course, be sure you securely reattach the stabilizer bar and reinstall the shield once the new pipes and mufflers are in place.

To install the X pipe, the original intermediate pipe must be unbolted at the rear, from the cat-backs, and cut off up front, several inches to the rear of the "cats," eliminating the original H crossover. The X pipe slips over the ends of the intermediate pipe and is clamped in place (stainless steel clamps are provided) and bolts up aft to the cat-backs, in the factory location. No welding whatsoever is required to install either the cat-backs or the X pipe.

The finished installation looks and fits great. The four large, round, polished stainless tips really brighten and beef up the back end of a C5. The small billet aluminum nameplate that connects the right and left halves of the system is a nice touch.

I was quite surprised by our test results, both the "numbers" off the Dynojet and in our noise level tests, using my hand-held decibel meter (Radio Shack, PN 33-2055). Baseline horsepower and torque output was about what I expected from a totally stock C5 with an automatic trans. The gains from the MagnaFlow muffler assembly were substantially higher than I expected, and both the horsepower and torque gains were across what portions of the powerband we could measure. The subjective (measureable) results from the X pipe installation fell short of my expectations. (See charts for comparative results.) Objectively, the improvement in throttle response is both noticeable and there at all times. The response is both crisp and more immediate, to part and full throttle inputs.

The Wide Open system proved to make less noise, at least as measured in decibels, than did the stock setup in four of our five tests. (Again, see the charts.) Objective evaluations: The exhaust note, both inside and out, is smoother with the X in place, and the car actually feels like it's running slightly smoother. I think it may also be minutely quieter inside with the X. There's little or no resonance. The exhaust note is deep and, for lack of a better way to explain it, authoritative. It doesn't make a lot of noise, although the volume definitely picks up at wide-open throttle--if you want a deafening roar, this ain't the one. However, the sound that comes out the pipes is very business-like, it has presence. You know just by the sound that it's a car you don't mess with.

Overall, I'm as happy as could be with the new exhaust. I'm still surprised at how sizable a power gain the car got from the MagnaFlow system, and I'm still surprised at the large amount of that gain that came from the mufflers. And I think the sound, both tone and the volume, is great. After all, thunderously loud is cool for Sting Rays and Stingrays with side pipes, or for Harleys, but gets tiresome everyday.



MagnaFlow Tech Center installer Matt Wideen removes the stock right-side muffler from our '00 coupe. Slipping the left-side muffler out of a C5 is a no-brainer; the right side takes a little more effort. The MagnaFlow crew offered a couple tips to simplify the job. Disconnect the rear stabilizer bar from the rear crossmember, leaving the end links connected, and swing it down and out of the way. This gives a lot more working room.



Also unbolt and remove the stamped metal shield from the right side of the gas tank. This also gives a noticeable gain in maneuvering room. Once the installation is completed, be absolutely certain to re-install the shield and remount the stabilizer bar.



Here's a look at the original intermediate pipe with its "H" crossover (arrow), before work was commenced. This view is looking forward, towards the catalytic converters. The square at the top of the picture is the automatic transmission's pan.



This view is looking aft, from the left front, after the "X" pipes and the "Wide Open" cat-back installation had been completed. The catalytic converters are in the upper left corner, and the X section is slightly to the right and below the center. The X pipe assembly bolts in place, once the rear portion of the original H pipe has been cut off a 1-1/2 feet or so behind the cats.

Hameed

MagnaFlow technician Jim Gose told me that the factory H crossover had too small an opening to be very efficient, and to prove his point cut the H apart.



The hole within a 2 1/2-inch diameter pipe was no more than a 1/2-inch diameter.



Details count. Matt (with his back to us) and Jim used a small carpenter's level to make certain that the exhaust outlets lined up as well as humanly possible.



Purely a personal opinion, but I think the stock '97-00 exhaust tips are totally unsuitable for the rest of the car--uninspired looking and way too small to be in proportion to the car. Besides, a Corvette needs an exhaust system that looks and sounds authoritative, and the factory system does neither.



Here's an interesting contrast in appearances--the stock left-side cat-back (right and to the rear) and the MagnaFlow Wide Open left-side assembly, in all its polished/big tips glory.



We're quite happy with the looks, but getting a whopping 15.8hp gain, at the tires and through an automatic transmission, was a much bigger treat. The horsepower and torque gains are more than enough to really feel, especially since the increases in horsepower and torque were across the powerband. The new exhaust note, deep and potent yet quiet, is just icing on the proverbial cake.

GSteg

iTrader: (15)

just out of curiosity, how much was the intake?

Hameed

$250.00 or thereabouts.....

RMMGS4

iTrader: (5)

Good info Hammed.

Thanks !


You got me thinking about an x - pipe real hard.

At the moment I still prefer a stealth sound.

Right now the car is near stock at normal cruising. Only at WOT does it turn Jekyl & Hyde !

Sound like the x-pipe can actually reduce the sound. So if I just replace my center resonator and keep the stock twin resonators, I might be able to keep the same volume as now, but with some more power gain from the x-pipe.