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08-12-2004, 10:43 AM
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#1 |
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Registered User
Join Date: Jun 2004
Location: Gilbert, AZ
Posts: 67
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Dual Exhaust
Question for you guys....
Want to put dual exhaust on my 98 5.7 4x4, looking at flow master mufflers. They offer a wide variety of sizes and styles, like 2.25" in 2.25 out or 2.25" in and 3" out. 2 or 4 chamber, etc. Want to do a cat back system. Just wondering what is the best application for the best performance. Any experience or help would be greatly appreciated.
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'98 Chevy Silverado Ex Cab Z-71 '02 GMC Yukon SLE 4x4 |
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08-12-2004, 11:02 PM
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#2 |
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Registered User
Join Date: Mar 2001
Location: Medicine Hat, Alberta, Canada
Posts: 1,508
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All Flowmaster system for that truck I found were really a single exhaust. I got the 2.25 in/out with tailpipes out each side, cause that is what my wholesaler had in stock(impulse buying you know). If you want dual tailpipes, Flowmaster makes an American Thunder with 2.25 tailpipes out each side, or two 2.25 pipes out one side. The other system is a 3.00 out the pass side. None are any better for performance then any other. You will find a decent performance gain, and a mileage improvement. The Flowmaster system was the best mod I have done to my truck from a performance standpoint. You will find it a little loud if you pull a trailer at highway cruise, and if the engine lugs a little, it tends to echo a bit, but I really have no regrets
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98 GMC Sierra Ex Cab, cowl hood, Euro LED lights, 30 bar billet, Whipple Supercharged 350 Vortec: Forged flattops, E-Tec aluminum heads, Comp Cam, Scat crank and rods, Granatelli Mass air flow, Headers, Flowmaster exhaust , Complete MSD Ignition, Custom Tuning, intake spacer , ported throttle body, AC Delco port injection upgrade, Roller Rockers, Power Pulleys. Gear Vendors Overdrive. Soon to hit a dyno. 2/4 drop(for now). 95 Chevy S-10 Ex Cab 4.3 5 Speed 2/3 drop, Euro lights, billet grill, More to come. The Daily Driver |
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08-13-2004, 02:25 AM
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#3 |
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MooMoo
Join Date: Feb 2004
Location: Shapleigh, Maine
Posts: 2,424
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Ive got a set of flowmaster 2.25 in and out on mine and am truely impressed, I also at the same time threw on a high flow air filter I get about 20 mpg.
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08-13-2004, 10:30 AM
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#4 |
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Registered User
Join Date: Jun 2004
Location: Gilbert, AZ
Posts: 67
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So did you guys use 2 mufflers instead of the 1 stock set up? Or did you use the 1 flowmaster with 2 pipe exit? Is it worth going to two mufflers or is 1 sufficient? Seems like from a performance point, 2 would be better.
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'98 Chevy Silverado Ex Cab Z-71 '02 GMC Yukon SLE 4x4 |
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08-13-2004, 10:31 AM
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#5 | |
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Registered User
Join Date: Jun 2004
Location: Gilbert, AZ
Posts: 67
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Quote:
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'98 Chevy Silverado Ex Cab Z-71 '02 GMC Yukon SLE 4x4 |
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08-13-2004, 05:20 PM
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#6 |
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MooMoo
Join Date: Feb 2004
Location: Shapleigh, Maine
Posts: 2,424
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all I did was exhuaust and k&n filter charger, and of course baby the throttle, I get on average about 350 miles to the tank if I wait till 1/8th of a tank, pretty sure its a 25 gallon tank, better than my old dodge v6
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08-13-2004, 05:46 PM
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#7 |
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Registered User
Join Date: Jul 2004
Location: Champaign/Danville, IL
Posts: 21
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On my 96 C1500 5.7 I originally had the dual inlet muffler, and what I ended up having a shop in town do was remove the dual inlet single exit muffler and replace it with two 40 series flowmasters with two 2.5" pipes and 3" tips out the rear
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1996 Chevy C1500 ext. cab short bed 350, complete rockford/infinity stereo, headlight flashers, true duals, euro clears up front, FIPK gen2, more is definately on the way..... 
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08-13-2004, 07:03 PM
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#8 | |
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Registered User
Join Date: Jun 2004
Location: Gilbert, AZ
Posts: 67
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Quote:
Did you have the same gas mileage result as 97silv5.7?
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'98 Chevy Silverado Ex Cab Z-71 '02 GMC Yukon SLE 4x4 |
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08-14-2004, 03:04 AM
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#9 |
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Registered User
Join Date: Oct 2003
Location: Broken Bow, OK
Posts: 1,385
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On my 97 2wd 5.7L I have 2 Flowmaster 40 series with 2.25" in /out.....Sounds great rumbles a little in cab but not annoying.
On my 99 Tahoe 4x4 5.7L I have a 2 inlet 2 outlet flowmaster. Sounds great too, not as loud as the 97, exhaust sounds great and only heard in cab while on throttle. With stereo on I don't hear it.
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95 K3500 SRW 5.7L Vortec 4L80e 4.10 G80 2001 GMC C3 6.0 AWD, Volant, 3/5 drop TBSS intake, HP tuners, pullies, 05 efans, 05 front brakes, etc. 2003 Tahoe Z71 Silverado front clip |
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08-17-2004, 07:34 PM
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#10 |
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Registered User
Join Date: Jul 2004
Location: Champaign/Danville, IL
Posts: 21
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My mufflers were 2.25" in/out with the tips being 3".
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1996 Chevy C1500 ext. cab short bed 350, complete rockford/infinity stereo, headlight flashers, true duals, euro clears up front, FIPK gen2, more is definately on the way.....
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08-17-2004, 09:37 PM
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#11 |
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Registered User
Join Date: Jun 2004
Location: Gilbert, AZ
Posts: 67
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Thanks guys, I know what my next project is....
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'98 Chevy Silverado Ex Cab Z-71 '02 GMC Yukon SLE 4x4 |
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08-17-2004, 10:18 PM
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#12 | |
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Workaholic
Join Date: Oct 2002
Location: Katy, TX
Posts: 1,589
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Quote:
350miles/25gallons=14MPG If you actually had 1/8 of a tank left: 25*(7/8)=21.875 gallons used So, 350/21.875=16MPG The way I learned to calculate fuel mileage is this. (assuming your speedometer/odometer is accurate) Fill up and drive till almost empty--fill up again and divide miles traveled by gallons used to refill tank. I think this is the only accurate way to calculate it (again, assuming speedo/od is accurate.) IMHO, peedo/odo problems are why so many people have inflated MPG claims. |
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08-17-2004, 11:43 PM
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#13 |
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MooMoo
Join Date: Feb 2004
Location: Shapleigh, Maine
Posts: 2,424
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I tend to do what you said but go by half a tank and fill up, then take how much the tank took and divide by miles. Even if I am a lil off I still do better than the dodge that I used to have.
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08-18-2004, 10:31 AM
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#14 |
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Registered User
Join Date: Jun 2004
Location: Gilbert, AZ
Posts: 67
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Just for your information, there are some great deals on flowmaster mufflers on ebay. I've found them for as low as $35 a muffler.
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'98 Chevy Silverado Ex Cab Z-71 '02 GMC Yukon SLE 4x4 |
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08-18-2004, 07:51 PM
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#15 |
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Senior Member
Join Date: May 2003
Location: ne florida
Posts: 2,665
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i put on 2 1/2 inch pipes on my v6[4.3] with turbo's on it also.
made a world of diff on mine. i went over 500 miles on 3/4 of a tank of gas from dayton tn to jacksonville fl.but i also dropped my tailgate and didn't run ac. has 25 gallon tank. |
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08-19-2004, 08:51 PM
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#16 |
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Registered User
Join Date: Jan 2004
Posts: 42
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I run a Force II Catback, nice mild tone at cruise, really comes to life when you get on it, I dont mind a single exhaust
Force II  I Got 17 MPG with a tent on top and 4 passengers, this from a recent trip to CA. (I ran premium fuel)
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1998 Yukon SLT K&N FIPK Flowmaster Force II Catback Exh. Hypertech 160 T Stat / Pwr Program G80: Locking, Rear Axle GT4: 3.73:1 Rear Axle Ratio KNP: Transmission Oil Cooler NZZ: Skid Plate Off-Road Z82: Trailer Pack Last edited by 1998 YUKON SLT; 08-19-2004 at 08:53 PM. |
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08-23-2004, 09:04 PM
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#17 |
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Registered User
Join Date: Jun 2004
Posts: 45
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Most cat back systems are single muffler (3 inch inlet, and dual 2.25 out) and if smog is going to be an issue most states will not allow dual mufflers. Check with the local laws to be sure. It is a B*t*h to put all that on only to remove it later. Just my 2 cents. I run a flowmaster 3in inlet and 2.5 dual out with 5 inch tips, a K&N air filter w/ a stage 2 chip on my '96' and all I can say is "wow". Hope this helps
 Rich
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PEOPLE THAT THINK THEY KNOW EVERYTHING ARE PARTICULARLY ANNOYING TO THOSE OF US THAT DO !! Dropped 93 Chevy Std Cab, 454 SS conversion, 20 in Centerlines, Wrap Around Ground Effects |
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