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CW
GenIII
 
6/25/2002
20:18:27
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 Subject: 4.7 exhaust idea...
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Message:
I just had a idea for the 4.7s with the precats and want to really upgrade the exhaust. I see lots of people wanting to get rid of the precats and get a better Y-pipe. You can have it custom built.
I was thinking of going with 2 1/4" pipes off of each side of the engine. Instead of trying to have a Y-pipe built get the carsounds cat from speedtweaks with the 2 1/4" dual inlet and have the pipes fabbed from the manifolds to the cat. It has a 3" outlet in my case I would have to buy another muffler but could keep my tail pipe.
No more worries about the y-pipe because it won't have one. Just extend the wires for the O2 sensors and put them in the pipe behind the cat. No check engine lights may even pass emissions. Put the emphisis on MAY pass.
2001 4.7HO RC 5sp 3.92 LSD
Click on thumbnail for mods.
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Horbedarn
*GenIII*
6/25/2002
23:52:23
|  RE: 4.7 exhaust idea...
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Message:
I was thinking doing the same thing pretty much. I was going to go 2 1/4" off each side of the engine and go to a 3" collector. Then go into a 3" in and out cat. Then run 3" back to the muffler and then split it with 2 1/4" duals out the back. There is a guy trying to run a group buy on Car Sound cats right now. I just don't want to loose too much low end and I need to pass emissions.
2000, CC, SLT, 4x4, 4.7, 3.55, Auto
MBRP Dual Exhaust Cat-Back, JBA Headers, 72mm TB, 4" Z-Tube
3923's, 180 T-Stat, IAT Adjuster
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CW
GenIII
6/26/2002
08:53:10
| RE: 4.7 exhaust idea...
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Message:
Yeah I forgot you could buy the collector as well. Torque isn't as big of a issue with me as it would be you though.
2001 4.7HO RC 5sp 3.92 LSD
Click on thumbnail for mods.
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handi2
GenIII
6/26/2002
09:50:45
| RE: 4.7 exhaust idea...
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Message:
Curtis,
I have only one catalytic converter, by the tranny mount. No pre cats.
What would happen to my torque (I use torque more than HP) if I replaced the one cat with a high flow.
Would I need to replace the 68mm TB with a larger one..? That is no problem if I need to.
Thanks
http://photos.yahoo.com/handi254310
2002 Quad Cab SLT Plus 4.7 Every Available Option
Access Tonnoue Cover/Bedrug/360 Air Intakez/Jet Stage 2
180 Robertshaw/Roadmaster Active Suspension
Street Scene Grill Inserts
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CW
GenIII
6/26/2002
14:30:09
| RE: 4.7 exhaust idea...
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Message:
When I took out my third cat (one over the cross member) I lost no torque. I gained nothing down low but let it rev better. I would think the same result would be with yours as well.
2001 4.7HO RC 5sp 3.92 LSD
Click on thumbnail for mods.
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Demon Dakota
DakotaEnthusiast
6/26/2002
16:15:38
| RE: 4.7 exhaust idea...
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Message:
I have removed my third cat as well, but I'm running true duals. I've gotten no Check engine lights, and it passed emmisions (had a buddy test it). I "might" have lost a slight amount of torque, but the HP is definitely up, and the RPM's come much quicker. Mid range and top end acceleration is also noticibly improved. I still have the stock throttle body right now, but that will soon change as well. It gets better in town mileage, and much better highway mileage. Plus it sounds mean as hell. Just my $.02 worth...
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Muzzy
GenIII
6/29/2002
05:03:08
|  RE: 4.7 exhaust idea...
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Message:
I noticed my truck pull harder from about 3500 RPM and up when I gutted my third cat. I am currently looking for a local shop that will do some custom exhaust for me. I want to eliminate the precats and use those Kat Boxes from KRC. I was going to use 2 1/4 from my headers to a Flowmaster Y pipe and 3" the rest of the way back. There aren't any emissions tests here or inspections.
-Muzzy
2001 EC Dakota 4x4 - 287ci V8 - 5 Speed - 3.92 gears/w Sure Grip
Borla Stainless Steel Headers - IAT Adjuster
Flowmaster Force II Cat Back - Ported TB/Custom Cold Air intake
H&K USC Security System
Coming Soon - head porting/ install HO cams & valve springs
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