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1999 Silverado/Sierra--Dual Exhaust questions
I'm considering adding dual exhaust to my
Silverado 5.3 V8 Long Bed Regular cab. I've seen
several trucks that have had this done. The 5.3
sounds great but my main interest is increased fuel
mileage. I regularly drive this truck above 80 mph
for extended periods. Am wondering if anyone has
actual before/after information. This truck has two
catalytic converters and it's therefore a breeze
to add true duals.
Any info would be greatly appreciated
Silverado 5.3 V8 Long Bed Regular cab. I've seen
several trucks that have had this done. The 5.3
sounds great but my main interest is increased fuel
mileage. I regularly drive this truck above 80 mph
for extended periods. Am wondering if anyone has
actual before/after information. This truck has two
catalytic converters and it's therefore a breeze
to add true duals.
Any info would be greatly appreciated
0
This discussion has been closed.
Comments
I should be getting my 2000 Silverado Reg Cab Sportside 4.8 In about 5 weeks...
Im going to hook up a dual exhaust system on it as soon as it comes in..
Basically what they do is just cut the two pipes leading into the huge GM muffler and put on two flowmaster mufflers with 2 1/2 inch chrome tip tail pipes.
This will not void your warranty from what i heard.. now if your talking about headers also ... then yes.
I heard that their is supposed to be a 10-20 hp increase when doing this...
Of course that is what your rights are it doesn't mean the dealer won't try to tell you that you voided your warranty on other parts.
Mike
you are exactly correct. the massey vs ferguson act states that your warranty can not be voided unless the aftermarket part that was replaced can be proven to have caused the failure of the warranted part. and of course, whatever parts are replaced will now no longer be convered under warranty.
My dealer pulls this every time I am in there. I promptly shut their sewer hole by stating my rights under this act. Its a CYA on their part and so I CYA mine with the massey vs. ferguson act.
Tee heee heee!
You will get very mild tones from Gibson. Jardine, I am not sure about sound tones. Flowmaster, if you want low to mid noise, I would go with the 70 series.
If I were most concerned about performance, I would go with Gibson. Gibson's catbacks are rated very high, but don't offer much sound improvement.
I chose the Magnaflow because it offers good performance increases and a VERY SERIOUS tone as well.
Gibsons website is www.gibsonperformance.com
Flowmasters website is www.flowmastermufflers.com
Gibsons site has wav files of recorded trucks with the gibson catbacks installed. Unfortunately they are recorded on Ford F150 trucks so it won't be exactly the same exhaust notes as would be on a Silverado.
My exhaust is a single 3" pipe in to a 2 chamber Magnaflow muffler, then 2.5" dual pipe out the back for better scavenging effects. Ends with 3.5" Stainless Steel Slash Cut Tips.
My best advice is not to go with a true dual. Nobody I know that has done it was at all satisfied and went back to a single in dual out.
The cats limit most of the flow anyway. Pretty much, after the cat is just a sound preference. Not much is able to be gained in exhaust mods on these new trucks compared to the good years of more lenient emission laws.
http://community.webtv.net/dp2000/TRUCKFORCEACTION
Some mufflers use fibers to quiet down a muffler, some use strictly chambers like the flowmaster. Some use both.
A 2 chamber will be louder interior and and exterior than a 3 chamber. Some say that the 3 chamber mufflers are just as loud exterior wise, but less interior resonance. I did not find that to be true in my case, but it may just be a difference in muffler types or a difference in how other people interpret interior resonance, etc.
I think 35 hp is wishful thinking on these new trucks. The catalytic converters are the biggest restriction in flow. Even using a freer flowing catback exhaust will most likely not gain 35 hp on a stock truck. Maybe in the higher hp "built" motors. The more of other mods that you do, the more gain you may see from the catback.
More realistically, I would say you might gain 20 hp and around 15 lbs torque.
Hey Zbad71 you've made a few, how should I say, "friends" on some of the other post. Hang in there! Thanks for the help..
I think you will get "some" level of fuel economy increase with all exhaust mods. As long as you don't expect miracles, you will be satisfied. I picked up 1-2 mpg increase with the exhaust I went with. Some of that may be from it getting more and more broke in though too. I would say 1 mpg is a "safe" assumption for a catback mod on these new trucks.
Take care.
Did I say anything that would offend? I have to second guess everything around here to make sure.
Since the cats are most of the restriction of the exhaust system, I can see where some significant gain would be had. However, by removing the cats, it may affect the scavenging effect of the system and could "reduce" torque and hp in the low end.
In my opinion, its always risky messing with emissions, both with the law and with possible problems it could cause with the vehicles driveability. However, I have heard others who have done it, so there must be a way around both the aforementioned.
Take care.
Summit has better selection, though, so if you're looking for a specific racing part, they're the better bet. For the Borla exhaust, I'd go with JCWhitney if you can get the 15% off (I can give you my catalog's 15% off code and part number if you like, but it expires on Dec. 31st which may be sooner than you were planning on buying). At $600 catalog list price, you'd save $90. JCW also carries Gibson exhaust, which are not stainless, but they're aluminized and they cost only about $300.
-powerisfun
I think Performance Products sells Borla exhausts too but it's been a while since I was in the market.
is this good for a custom job??
If you have a '99/'00 Silverado/Sierra, I don't
think I'd bother getting shorty headers. In one of the articles on the JBA Racing page (http://www.jbaracing.com ), it shows a picture of the stock exhaust manifold removed from a 5.3L engine and it looks very unrestrictive (a lot less restrictive and better designed than the stock manifold of my Vortec 5.7L). It looks like a well designed manifold and resembles a shorty header already, so it probably has the similar siphoning (i.e. scavenging)
characteristics. This was probably one of the important ways that GM got the power up on these new engines (Good show GM!). Unless you can find a set of smog-legal long tube headers (lots of luck there!), or you just want the look of chrome headers in your engine compartment, I wouldn't waste the money.
-powerisfun
If you got to have em Arizona Speed & Marine has them for the new Silverados... starting at $800.00 I'am happy with my JBA shorties...$400.00
Awesome Dave-40 Commander In Chief/U.S.TruckForce
http://community.webtv.net/dp2000/TRUCKFORCEACTION
I've heard that too, but according to the JBA website, long tubes increase torque in the lower rpm range which would seem to be more to a truck-owner's liking. The "Chevrolet SysteMax" article shows that the long tubes increase low-end torque better than the shorties. The engine they tested is a Target Master Chevy 350 with first ~370 hp and then after increasing the compression ratio ~400 hp. Understandably that is still a relatively high horsepower engine, but it's less than 100 hp more than the GM 6.0L.
Anyway, I ended up getting Flowtech brand headers for my 5.7L and they're great. Definitely more power especially in the 2400 rpm and higher range.
About the same (or at least less noticeable) at lower rpms.
-powerisfun
Im just going to Y into a flow and dual out of that, making my nice low end sound and hopefully gaining some power and maybe if i stretch it enough maybe even some gas mileage...
One other guess is a bit more cynical. Is it possible that the manufacturers and the after-market folk are washing each other's backs?
-powerisfun
P.S. I just added a cat-back exhaust to my truck and you can read about it in topic #1214 "Headers on late model trucks". It's a '98, but the exhaust set up is very similar (if not a direct carryover) to the new trucks.
Headers definitely do affect emissions because their sole purpose is to scavenge (i.e. like a siphon effect) more exhaust from the cylinder (so exhaust is not only being pushed out but pulled out as well). Shorty headers are one of the smog-legal varieties and they're probably only effective if your manifold is not well designed (e.g. the manifolds on a chevy 350 are both restrictive and horizontal for very little scavenging, however the new GM Vortecs' manifolds look very well designed and headers would probably be less effective there).
-powerisfun