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I have a '91 F-150 Short Box with an EFI I6 with a split exhaust manifold with 2.25" exhaust pipe. I have been told that trying to dual it off is pretty much pointless and only costs you more money so I decided against it. So what I want to do is go with 2.25" pipe from the cat into a Dynomax Super Turbo muffler and "Y" it off for dual tips straight out the back. My intentions are to get as deep of a tone as I can out of the 6 cylinder and to improve horsepower, torque, and fuel economy a little bit. Will I face any problems sticking with stock manifolds into an after market muffler? I do quite a bit of off roading, so is two tail pipes straight out the back of a short box still safe? Anything else I should be concerned about? If not, how does this setup sound?
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So you have 3 cylinders running to each half of the manifold?
I would just run 2" piping from each set of 3 cylinders to a 2.5" maybe 2.75" pipe. That is plently large for that 4.9.
Dynomax SuperTurbo is a nice muff, deep, mellow, nice sound. Good choice.
Many people run high flow exhaust systems with stock manifolds. Full length headers just add more power and sound!
Pipes out the back should be fine wether offroading or not
I would just run 2" piping from each set of 3 cylinders to a 2.5" maybe 2.75" pipe. That is plently large for that 4.9.
Dynomax SuperTurbo is a nice muff, deep, mellow, nice sound. Good choice.
Many people run high flow exhaust systems with stock manifolds. Full length headers just add more power and sound!
Pipes out the back should be fine wether offroading or not
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Yeah, its the first three cylinders into one pipe and then the second three into another and the join at what I think is the first cat? Anyway, after they join, it's 2.25" pipe through my second cat and into my muffler and 2.25" all the way back. I really wasn't planning on changing any pipe diameters mainly because I don't have the money for a header(s). So if my dad will let me, I was just going to cut off the second cat (or gut it out) and go into the Super Turbo. And depending on how much money that all costs I might have it twined off straight out the back. And just in case I want to put a header on it sometime down the road, would 2.25" still be alright? Or would buying a header with only 2.25" outlet drain some of my potential power?
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I would just cut off both cats and run a 2.5" SI/SI CarSound cat. No sence in gutting one, the sound will be weird like that and you can't pass the sniffer.
I would probably run a 2.5" collector from that header back.
Best best to get a 2.5" SI SuperTurbo, that way you have some growing room if and when you get a header installed.
I would probably run a 2.5" collector from that header back.
Best best to get a 2.5" SI SuperTurbo, that way you have some growing room if and when you get a header installed.
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I live in Idaho where the don't have emissions tests so I just have to get past my dad if I want to get rid of the cat. I don't have a ton to spend on this either and a decent hi flow cat costs about $100 extra. I was wondering if I should try to keep stock cat and just go with 2.5" pipe or cut it off and go with 2.5" pipe. What problems would I be looking at if I did one or the other?
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I have seen those high flow cats for far less than $100. Start by checking out this link:
http://search.ebay.com/ws/search/Sal...0&BasicSearch=
I have used Carsounds on many applications and they work great.
Now that those cats can be picked up so cheap, I'd ditch both stock cats and run that highflow one with a 2.5" SuperTurbo
http://search.ebay.com/ws/search/Sal...0&BasicSearch=
I have used Carsounds on many applications and they work great.
Now that those cats can be picked up so cheap, I'd ditch both stock cats and run that highflow one with a 2.5" SuperTurbo
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Are you sure that the box that joins the two manifolds is a cat or is it just an encased Y pipe? If it is just a Y pipe, then removing it would only be costing me extra money. If it is a cat, then replacing it with a high flow cat would force me to buy a Y pipe to join them and then buy the new high flow. If I had to do that, do you suggest that I make the single outlet end of the Y pipe 2.5" or stick with 2.25"?
One other question came to me today. Which would create better sound for me? Dual tips or a single turn down tip a little after the muffler?
One other question came to me today. Which would create better sound for me? Dual tips or a single turn down tip a little after the muffler?
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That front box is a precat. You could just cut it off, run about 6" of pipe from one of the collectors to the cat the hook the other collector to it...look at my UserGallery for a pic of what I am trying to explain.
If you are going to make a new y-pipe I'd go for 2.5".
A turn down or dump is pretty loud and drone a bunch. I'd just go for a single rear exit or a dual rear exit. I'd also stay away from tips as they only make stuff resonate worse.
If you are going to make a new y-pipe I'd go for 2.5".
A turn down or dump is pretty loud and drone a bunch. I'd just go for a single rear exit or a dual rear exit. I'd also stay away from tips as they only make stuff resonate worse.