FlowMaster says 4.6 is designed to use a single muffler!!
#1
09-05-2001 | 01:50 AM
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From: Longview, WA USA
FlowMaster says 4.6 is designed to use a single muffler!!
I talked to people at both MagnaFlow and FlowMaster today over the phone and I asked them, "What do you recommend for my 4.6 V8? Both of the people said quite emphatically, "Your engine, with two oxygen sensors, was designed and is set up to use a single muffler system for proper back pressure. If you alter your exhaust to true dual exhausts, you will definately have to buy a new chip to tune the engine to accept the new readings and it will cost you a lot of money to have true duals. And when you're all done, you won't have gained any benefits for street driving."
MagnaFlow recommended a single muffler with a 3" inlet and a 3" outlet, and 3" pipe with a 4" tip. The guy said I could go for a two outlet muffler with 2-1/4" outlets. I said, "How about 2-1/2" outlets and pipe? He said, "That won't allow the proper back pressure you need for that engine."
FlowMaster seemed to agree perfectly. However, that tech person seemed to think 2-1/2" outlets would be alright too. But what difference does that make when you're going to weld 3" chrome or stainless tips out where you'll see the pipe.
I told them I wanted a nice, mellow rumble at FlowMaster and the tech suggested the Series 50 Street Performance Muffler.
So, I guess it's more important to have the proper back pressure and let the oxygen sensors do their job. Maybe that's why all these guys, who have altered their exhausts to true duals, are seeing oxygen sensor lights come on their dash. I suspect that is the problem right there.
Does anyone have any additional research to add to this puzzle?
MagnaFlow recommended a single muffler with a 3" inlet and a 3" outlet, and 3" pipe with a 4" tip. The guy said I could go for a two outlet muffler with 2-1/4" outlets. I said, "How about 2-1/2" outlets and pipe? He said, "That won't allow the proper back pressure you need for that engine."
FlowMaster seemed to agree perfectly. However, that tech person seemed to think 2-1/2" outlets would be alright too. But what difference does that make when you're going to weld 3" chrome or stainless tips out where you'll see the pipe.
I told them I wanted a nice, mellow rumble at FlowMaster and the tech suggested the Series 50 Street Performance Muffler.
So, I guess it's more important to have the proper back pressure and let the oxygen sensors do their job. Maybe that's why all these guys, who have altered their exhausts to true duals, are seeing oxygen sensor lights come on their dash. I suspect that is the problem right there.
Does anyone have any additional research to add to this puzzle?
Last edited by Bill Voyles; 09-05-2001 at 02:00 AM.
#2
09-05-2001 | 02:34 AM
Senior Member
Joined: Dec 2000
Posts: 724
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From: EL Sobrante, CA ,
The correct exhaust
Hey Bill
When you call these companys you will get a different answer from all of them. I have a 2001 with a 4.6, here is what i did, i had the factory Y pipe replaced with a high flow unit and had a piece of 3" pipe run back to a 40 series flowmaster, single 3" in/ duel 2-1/2 out, with 3-1/2" chrome tips. There was a very noticable power increase, as well as a noticable gain in low and mid range power. And my gas mileage went up as well. I get between 17-20 miles per gallon depending on how i drive.
I hope this helps you out.
Larry.
When you call these companys you will get a different answer from all of them. I have a 2001 with a 4.6, here is what i did, i had the factory Y pipe replaced with a high flow unit and had a piece of 3" pipe run back to a 40 series flowmaster, single 3" in/ duel 2-1/2 out, with 3-1/2" chrome tips. There was a very noticable power increase, as well as a noticable gain in low and mid range power. And my gas mileage went up as well. I get between 17-20 miles per gallon depending on how i drive.
I hope this helps you out.
Larry.