Need help to build custom exhaust.

[benztech82]

Hey fellows,

I want to change my exhaust muffler, again. Right now i have flowmaster super 50suv and i dont like it cause I lost mid and top end acceleration. I want to use dynomax xflow 2.25 dual in and out for gas scavenging and ideally it should be routed all the way to the back to lower the noise. So now my dilemma is that i dont know if i should run true dual pipe to the back after muffler or if i can get away with adapter 2 in to 1 but maybe 4 inch to keep the flow volume high.

If any of you tried any of mentioned configurations or maybe we have a tech specialist in exhaust pipes, i would really appreciate your input.

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[Inv4drZm]

Hey fellows,

I want to change my exhaust muffler, again. Right now i have flowmaster super 50suv and i dont like it cause I lost mid and top end acceleration. I want to use dynomax xflow 2.25 dual in and out for gas scavenging and ideally it should be routed all the way to the back to lower the noise. So now my dilemma is that i dont know if i should run true dual pipe to the back after muffler or if i can get away with adapter 2 in to 1 but maybe 4 inch to keep the flow volume high.

If any of you tried any of mentioned configurations or maybe we have a tech specialist in exhaust pipes, i would really appreciate your input.

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I don't think there is any way you'll be able to route a 4" tube over the axle, and 4" is waaay too big. 4" is probably triple the area of a 2" tube (the math is easy I'm just lazy).

Volume is important, but what you should really care about is velocity.

If I were to design a good top-end system, you would want it to look something like this. This is what I built.

All 2.5" tubing with an x pipe shortly after the headers to help pull the opposite side's gases out. Equal length between the headers and x pipe to help separate the exhaust pulses. 2 straight-through magnaflow mufflers and a dump before the axle.

If you wanted yours routed to the back bumper area, I would just go single tube. Dual 2.5" tube is probably possible to fit, but not sure its worth the headache in this situation. If you wanted some hp gains, I would build or buy a better Y pipe using a less restrictive merge, then mate it to a straight-through muffler, then adapt it to use your stock tailpipe section. I did this before my current setup and it sounded nice.

 

[benztech82]

Your setup looks flawless our pipes are 2.25 though, isn't it ? Also is this setup "wife loud" ? I understand that straight through design is always louder but maybe if I would use larger muffler and 2.25 in out it would make it more tolerable ?

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[Inv4drZm]

Your setup looks flawless our pipes are 2.25 though, isn't it ? Also is this setup "wife loud" ? I understand that straight through design is always louder but maybe if I would use larger muffler and 2.25 in out it would make it more tolerable ?

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Our pipes are 60mm which is basically 2-3/8".

My dual system without cats is pretty loud, but the single straight-through 18" muffler with 2 cats is moderate, and if you have all 4 cats and used a longer single muffler then it should be pretty mild.

 

[benztech82]

Our pipes are 60mm which is basically 2-3/8".



My dual system without cats is pretty loud, but the single straight-through 18" muffler with 2 cats is moderate, and if you have all 4 cats and used a longer single muffler then it should be pretty mild.

My first setup was 4 cats, and 2 straight flow extra long hot rod glass packs and it sounded like a jet plane to my wife and it got too me too after 6 month. But truck pulled amazing with proper fuel mapping.


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[benztech82]

I'm keeping all 4 cats, so just x pipe and single muffler, dual inlet/outlet and dumps before the axle i guess. Or true dual like yours with maybe larger "cans" to cut the noise as much as possible

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[Direwolf82]

4" would be completely overkill, and not the good kind of overkill but the impossibly large headache kind.
My old 800hp Camaro was running through 3" exhaust, putting down 10 second quarter mile passes with no breathing issues. I'm betting our trucks can breathe just fine through 2" pipe if absolutely needed, I would not do that or recommend it but I have a feeling it would work out.
Move to 2.5" single, easier to build the system and cheaper on material. Build it in stainless and enjoy for years to come. At least that's what I'd probably do.
Also agree with whoever mentioned it earlier, make a new crossover pipe. The stock one does look pretty crappy and probably isn't helping anything over 2500rpm.

 

[benztech82]

I was doing some research and right now i'm thinking of using magnaflow x pipe then cherry bomb vortex dual 2.5 in, single 3in out to the side rear bumper.
Vortex design seems like the quietest of all straight through mufflers.

I agree 4" is overkill.

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[Inv4drZm]

I was doing some research and right now i'm thinking of using magnaflow x pipe then cherry bomb vortex dual 2.5 in, single 3in out to the side rear bumper.
Vortex design seems like the quietest of all straight through mufflers.

I agree 4" is overkill.

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I would still say 3" is overkill. Like I mentioned you want velocity, and when exhaust gases cool down near the tailpipe, they lose velocity. Reducing tube diameter helps keep the velocity up.

 

[Direwolf82]

Large bore exhaust piping is really best for large displacement, high rpm applications at full throttle. Going to a true dual 2.25 inch system would drastically improve airflow over the stock system and probably be a little easier to bend and snake it in. Saying that I'd put in a 2.5 inch system, well designed should be able to support the 300 horse range no problem.

 

[benztech82]

I would still say 3" is overkill. Like I mentioned you want velocity, and when exhaust gases cool down near the tailpipe, they lose velocity. Reducing tube diameter helps keep the velocity up.

I really appreciate your input on this. Can you explain how does it work, each bank has 2.25 diameter which goes in to single 2.25 pipe, wouldn't that create more of a restriction ? Honestly my logic is telling me that 2.25 x2 jammed in to a single 2.25 pipe should create restriction mid/top rpm.

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[Inv4drZm]

I really appreciate your input on this. Can you explain how does it work, each bank has 2.25 diameter which goes in to single 2.25 pipe, wouldn't that create more of a restriction ? Honestly my logic is telling me that 2.25 x2 jammed in to a single 2.25 pipe should create restriction mid/top rpm.

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Ideally the pipes would merge into an x, or if it was a single system, a y, shortly after the headers. This is where exhaust is traveling the fastest and pulses are most separated, which is why scavenging is most effective here. In the tailpipe section the exhaust 'evens out'. Pulses join together, temps decrease substantially, velocity slows down, when velocity slows, pressure increases. A larger tube here, if anything, compounds the problem.

You can look up max engine horsepower for exhaust tubing for dual and single systems, and they will tell you a single 2.5" tube is fine up to 250 to 300hp. I believe this is probably near the headers/catback, and not at tailpipe temperatures.

You're more than welcome to try a 3" tailpipe I just think a 2.5" will be easier to route and better in some performance areas.

 

[benztech82]

Ideally the pipes would merge into an x, or if it was a single system, a y, shortly after the headers. This is where exhaust is traveling the fastest and pulses are most separated, which is why scavenging is most effective here. In the tailpipe section the exhaust 'evens out'. Pulses join together, temps decrease substantially, velocity slows down, when velocity slows, pressure increases. A larger tube here, if anything, compounds the problem.

You can look up max engine horsepower for exhaust tubing for dual and single systems, and they will tell you a single 2.5" tube is fine up to 250 to 300hp. I believe this is probably near the headers/catback, and not at tailpipe temperatures.

You're more than welcome to try a 3" tailpipe I just think a 2.5" will be easier to route and better in some performance areas.

I have measured pipe size between secondary cat and where my Y-pipe used to be and it's original piping that I was measuring. It's 1.9" not even 2.25"