3.5" or 4" Single Dump Exhaust?
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On The Tree
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3.5" or 4" Single Dump Exhaust? I decided that I want to do a single dump exhaust on my 00 Formula. I dont want to do dual dumps. My engine mods are 243 heads, Comp Cam XR265-15 212/218 Duration, .558/.563 Lift, LS6 Intake, and Pacesetter longtubes. I'm going to be using a Flowmaster Y merge pipe. My question is if I should do a 3.5" exhaust or 4"? Also, if I decide to run the exhaust all the way to the back what size will work?
Might as well do the 4" now, I assume you will be making the car faster later and won't want to rebuild it again. Here is a thread from just a few days ago, and the other link has the part numbers if you do it that way. Best exhaust i have ever had
https://ls1tech.com/forums/generatio...ust-setup.html
here's the Y into a 4" merge, cutout, catback combo:
https://ls1tech.com/forums/generatio...ut-dumped.html
https://ls1tech.com/forums/generatio...ust-setup.html
here's the Y into a 4" merge, cutout, catback combo:
https://ls1tech.com/forums/generatio...ut-dumped.html
Last edited by BlackDuk98; Mar 8, 2015 at 08:54 PM.
FYI, your muffler options are very limited for either a 3.5" or 4" in/out bullet muffler that will fit after the Y-pipe merger exit. Furthermore all of your muffler option will be very loud, and with the FM Y-merger being so long you'll have even less room. Imo the only option that I found works good when dumped befor the rear-end assembly with running a Y-pipe is to stick with a 3" Y-pipe merger exit and run either a Dynomax #24219(4"dia. w/18"case, $50), Borla XR-1 #40085(5"dia. w/14"case, $137) or a Magnaflow #12876(5"dia. w/14" case, $109) . All will still be loud, but still very livable in a DD car. My suggestion for either a 3.5" or 4" y-pipe back exhaust is to NOT dump it, but run it over the axle tube an into a oval muffler that's in the stock location. Something like a Mufflex cat-back(3.5" or 4") or a Stainless Works 3.5" cat back .
Last edited by 99Bluz28; Mar 8, 2015 at 06:21 PM.
FYI, your muffler options are very limited for either a 3.5" or 4" in/out bullet muffler that will fit after the Y-pipe merger exit. Furthermore all of your muffler option will be very loud, and with the FM Y-merger being so long you'll have even less room. Imo the only option that I found works good when dumped befor the rear-end assembly with running a Y-pipe is to stick with a 3" Y-pipe merger exit and run either a Dynomax #24219(4"dia. w/18"case, $50), Borla XR-1 #40085(5"dia. w/14"case, $137) or a Magnaflow #12876(5"dia. w/14" case, $109) . All will still be loud, but still very livable in a DD car. My suggestion for either a 3.5" or 4" y-pipe back exhaust is to NOT dump it, but run it over the axle tube an into a oval muffler that's in the stock location. Something like a Mufflex cat-back(3.5" or 4") or a Stainless Works 3.5" cat back .
Good options listed here. I agree with there not being much room or options for mufflers before tha axle. When i did mine, i had to cut everything to the absolute limit, massage the floor and the muffler. I did mine the harder way because i still wanted the catback operational if i needed to be quiet, then the larger exhaust for power. The muffler like i did is not required, but if you dont like rasp, you will want it.
If you want a nicely made, easy install one final exhaust, a Mufflex setup is really nice. Also depends how sensitive the cops ears are in your area.
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For now im going to try the 4" FM merge with a Hooker Maxflow muffler dumped before the axle. If its too loud then I'll route it to the back similar to a Mufflex catback. I hear that the Hooker Maxflow is one of the quietest mufflers under normal driving. The setup I'm running now is a Hooker Aerochamber muffler welded into the stock 2.75 catback which seems to me like a big restriction. Car is my dd but I only drive like 4 miles everyday.
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haha just noticed 99Bluz28 was the other guy posting pics in this thread. OP, look this thread over to see what each of us is talking about:
https://ls1tech.com/forums/generatio...ut-dumped.html
Last edited by BlackDuk98; Mar 8, 2015 at 09:00 PM.
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Yea I have to modify the bump area for the passenger seat. I dont know how much until I get the parts. If it needs extreme modification I'll probably just make the exhaust run all the way back. Now I told two mechanic friends about my 4" set up and they say its way overkill and I will loose a lot off low end. So that got me thinking. From what I read a 3.5" diameter is good up to 500 flywheel hp. Is that correct?
Who? the OP with the Hooker Maxflow? or me?
haha just noticed 99Bluz28 was the other guy posting pics in this thread. OP, look this thread over to see what each of us is talking about:
https://ls1tech.com/forums/generatio...ut-dumped.html
haha just noticed 99Bluz28 was the other guy posting pics in this thread. OP, look this thread over to see what each of us is talking about:
https://ls1tech.com/forums/generatio...ut-dumped.html
Last edited by 99Bluz28; Mar 8, 2015 at 11:39 PM.
Yea I have to modify the bump area for the passenger seat. I dont know how much until I get the parts. If it needs extreme modification I'll probably just make the exhaust run all the way back. Now I told two mechanic friends about my 4" set up and they say its way overkill and I will loose a lot off low end. So that got me thinking. From what I read a 3.5" diameter is good up to 500 flywheel hp. Is that correct?
Imo, I don't think a single 4" pipe is going to hurt your power, it still flows less than duals 3" pipes.. and there's lots of people running dual 3" exhaust that make under 500fwhp. Imo if you think even with future mods you'll be above 465 fwhp then you might benefit from a 4" pipe. On another note at that same 465 fwhp I doubt you'll notice little to any difference from a 3.5" pipe. Now if later you were go forced induction without a doubt I'd go 4" without a second thought since you'll clearly benefit from it.
Last edited by 99Bluz28; Mar 11, 2015 at 09:58 AM.
Thread Starter
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I'm going to do a 3.5" single exhaust set up. After talking to a few friends I came to the conclusion that a 3.5" would be the best for my car. A 4" would be nice but I would probably need to run a turbo or supercharger to take advantage of it. I'm going to fabricate it myself. If its too loud for my taste then I'll route it to the back. I was looking on Summint and they basically sell everything one would need for a catback. I dont know if thats something Im capable of fabricating but for now I will focus on building my 3.5" exhaust dump then I'll go from there.
As long as that Hooker Max. Flow muffler is configured with a offset inlet so you can place most of the case where the rear seat hump would normally be it should be a problem.
Imo, I don't think a single 4" pipe is going to hurt your power, it still flows less than duals 3" pipes.. and there's lots of people running dual 3" exhaust that make under 500fwhp. Imo if you think even with future mods you'll be above 465 fwhp then you might benefit from a 4" pipe. On another note at that same 465 fwhp I doubt you'll notice little to any difference from a 3.5" pipe. Now if later you were go forced induction without a doubt I'd go 4" without a second thought since you'll clearly benefit from it.
Imo, I don't think a single 4" pipe is going to hurt your power, it still flows less than duals 3" pipes.. and there's lots of people running dual 3" exhaust that make under 500fwhp. Imo if you think even with future mods you'll be above 465 fwhp then you might benefit from a 4" pipe. On another note at that same 465 fwhp I doubt you'll notice little to any difference from a 3.5" pipe. Now if later you were go forced induction without a doubt I'd go 4" without a second thought since you'll clearly benefit from it.
I'm going to do a 3.5" single exhaust set up. After talking to a few friends I came to the conclusion that a 3.5" would be the best for my car. A 4" would be nice but I would probably need to run a turbo or supercharger to take advantage of it. I'm going to fabricate it myself. If its too loud for my taste then I'll route it to the back. I was looking on Summint and they basically sell everything one would need for a catback. I dont know if thats something Im capable of fabricating but for now I will focus on building my 3.5" exhaust dump then I'll go from there.
99BluZ is correct .... don't you just love it when guys get advise from some mechanic , or their friends or even exhaust shops that don't have a clue want the LS engine responds to performance wise . I think most of these guys saying this crap don't even have a modded LS engine . Let alone build , race, or test them.
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So far I have the Y-pipe merge welded in where the pacesetter y merge used to be. I went with a 3" to 3.5" merge. I tried setting it up for a single dump but my clearance will be only about 2". My car is lowered around 1.25". So I'm gonna run a full single catback. The muffler I'm gonna be using is a 21507 Hooker Aerochamber. This is center inlet/center outlet. I like the way it sounds but too much noise inside. So, the noise and clearance is what made me change my mind about dumping the exhaust.
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So this is the final build for my exhaust. Its a single 3.5 catback. I will post pictures of the system in the car when i get the car on a lift. All I have at home is jacks and jack stands but cant take any good pics. looks good and sounds good.
Yea I have to modify the bump area for the passenger seat. I dont know how much until I get the parts. If it needs extreme modification I'll probably just make the exhaust run all the way back. Now I told two mechanic friends about my 4" set up and they say its way overkill and I will loose a lot off low end. So that got me thinking. From what I read a 3.5" diameter is good up to 500 flywheel hp. Is that correct?
Thread Starter
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SkWiDsTyLe321 I was thinking about the dual exit too. Maybe I can do that later. use 2 mufflers. If I ever do forced induction I will definitely do a 4" or even dual 3". I feel a difference in the way the car picks up now but then I just replaced the clutch recently and upgraded to an aluminum flywheel so its probably that mostly.
you can do dual exit right now if you like the look of tips on both sides ... no 2 mufflers needed - just add a 90 & 45 degree bend (& piping in between) ... ill post a pic of mine later but i'm sure you know what i mean