Exhaust idea opinions

404NotFound

404NotFound

New member
Hey guys, I finally got a 4Runner. 2005 4.0 SE. I have used the search bar, YouTube, Google, etc. but I haven't really found a direct answer to my idea so I guess I'm here looking for confirmation that I'm going in the right direction. Also I hope I'm posting in the right section. I didn't know if this should go in maintenance/engine.

So from what I've gathered looking through the forum, our trucks benefit from back pressure. My educated guess is there has to be a happy medium, considering that the engineers at Toyota did design the exhaust system although logically it may not be at peak efficiency due to emissions standards. Therefore I speculate there must me a median between "too much" and "not enough" in terms of back pressure. For instance my Mustang basically has a straight exhaust but when I had Super 44s on my old F-150 it felt like it lost power.

So I've decided I really don't want a catback. Nothing against them but the reality is it's a bunch of money for a modification that is for sound with minimal horsepower/torque gains and if it is too free flowing, the possibility for loss.

I'm also in the minority. Yes, I adore the rumble of a fine V8 but since I have a 4.0, I don't necessarily want it to rumble low. I'd rather appreciate it for what it is and the sound it makes. I mean I don't want it to sound like I taped a Folgers can to the tail pipe but I like the sound of a nice V6 if it's done right.

So I thought, AFE stage 2 intake for cooler air in. Minimal gains but it does clean up the engine compartment and sounds nice. For the exhaust, I want to stick with the stock 2.5 inch setup but I was considering replacing the muffler with a Flowmaster 50 series (HD or SUV) a 40 series, or Super 44. Then, replace the stock resonator with the Flowmaster Hushpower 2 12" shorty, since it was designed as a resonator and my hope is that it would help with the potential drone. Then finish it off straight out the back with a split 2.5 in dual 3.5 out chrome tip on the passenger side. I know, it's not a truck look but being a Toyota I'm kinda trying to give that Supra or type 86 look. I know it probably sounds way off in left field compared to most of the wants usually expressed on here, but I just have a strong appreciation for the sound of a GOOD tuner car, like a Supra, GTR, STi, Evo, etc. I'm definitely not after the "Civic with a 16 year old wannabe street racer" sound, just something different that won't affect the performance negatively but also won't be obnoxious while I'm driving 50 miles to work round trip everyday.

I guess I'm just wanting to make sure I'm understanding the back pressure needs and potentially the sound I'm looking for based on the clips I've watched and reviews I've read on here. Please and thank you.

Of course the old :ballchain: already told me "it's gonna be our family car, don't f*** it up" when I told her I wanted a mount for my 12,000# winch with an LED light bar, so I need to be smart about this decibel wise in the cabin.
 
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Where did you hear that the 4runner like back pressure, for that fact where did you hear that back pressure is a good thing?
 
Back pressure is a good thing. At least on Harley engines it is. The cycle includes a little scavenging. Free flow pipes on a Harley and you've lost power. Do so in a way that accounts for the tiny bit of back pressure needed and you'll make great power. At least that's what we see in the HD engine power chase.
 
Velonici said:
Where did you hear that the 4runner like back pressure, for that fact where did you hear that back pressure is a good thing?
Click to expand...

He might be coming from the turbo world. With many internal waste gate turbo charged cars back pressure helps prevent boost creep (a mechanical issue where an internal waste gate set up can no longer handle the exhaust flow, which can really only be fixed by installing an external waste gate). I cannot think of why this would be an issue on a N/A engine though.
 
404NotFound said:
Hey guys, I finally got a 4Runner. 2005 4.0 SE. I have used the search bar, YouTube, Google, etc. but I haven't really found a direct answer to my idea so I guess I'm here looking for confirmation that I'm going in the right direction. Also I hope I'm posting in the right section. I didn't know if this should go in maintenance/engine.

So from what I've gathered looking through the forum, our trucks benefit from back pressure. My educated guess is there has to be a happy medium, considering that the engineers at Toyota did design the exhaust system although logically it may not be at peak efficiency due to emissions standards. Therefore I speculate there must me a median between "too much" and "not enough" in terms of back pressure. For instance my Mustang basically has a straight exhaust but when I had Super 44s on my old F-150 it felt like it lost power.

So I've decided I really don't want a catback. Nothing against them but the reality is it's a bunch of money for a modification that is for sound with minimal horsepower/torque gains and if it is too free flowing, the possibility for loss.

I'm also in the minority. Yes, I adore the rumble of a fine V8 but since I have a 4.0, I don't necessarily want it to rumble low. I'd rather appreciate it for what it is and the sound it makes. I mean I don't want it to sound like I taped a Folgers can to the tail pipe but I like the sound of a nice V6 if it's done right.

So I thought, AFE stage 2 intake for cooler air in. Minimal gains but it does clean up the engine compartment and sounds nice. For the exhaust, I want to stick with the stock 2.5 inch setup but I was considering replacing the muffler with a Flowmaster 50 series (HD or SUV) a 40 series, or Super 44. Then, replace the stock resonator with the Flowmaster Hushpower 2 12" shorty, since it was designed as a resonator and my hope is that it would help with the potential drone. Then finish it off straight out the back with a split 2.5 in dual 3.5 out chrome tip on the passenger side. I know, it's not a truck look but being a Toyota I'm kinda trying to give that Supra or type 86 look. I know it probably sounds way off in left field compared to most of the wants usually expressed on here, but I just have a strong appreciation for the sound of a GOOD tuner car, like a Supra, GTR, STi, Evo, etc. I'm definitely not after the "Civic with a 16 year old wannabe street racer" sound, just something different that won't affect the performance negatively but also won't be obnoxious while I'm driving 50 miles to work round trip everyday.

I guess I'm just wanting to make sure I'm understanding the back pressure needs and potentially the sound I'm looking for based on the clips I've watched and reviews I've read on here. Please and thank you.

Of course the old :ballchain: already told me "it's gonna be our family car, don't f*** it up" when I told her I wanted a mount for my 12,000# winch with an LED light bar, so I need to be smart about this decibel wise in the cabin.
Click to expand...

Google "Exhaust Back Pressure good or bad"

As for your muffler idea: it would not be my first preference. I do a lot of highway driving. One of the great things about the T4R is how quiet it is inside. Wind noise, exhaust and intake all take away from that.

By the way, love the user name. Good idea.
 
intake will give you a good growl on the engine side, as for the exhaust, a flow master 40 or 44 will make it sound ricey, I've been in one with a super 44 and it was obnoxious at any speed. super 50 has had good results and has a more mellow and deeper tone.
 
Velonici said:
Where did you hear that the 4runner like back pressure, for that fact where did you hear that back pressure is a good thing?
Click to expand...

I actually read it somewhere in a forum on this site. I didn't save it but I will try to look for it so I can source it. I should have from the beginning. I know too much back pressure is a bad thing, but alternatively on certain applications too much flow is bad as well.
 
Freyer said:
He might be coming from the turbo world. With many internal waste gate turbo charged cars back pressure helps prevent boost creep (a mechanical issue where an internal waste gate set up can no longer handle the exhaust flow, which can really only be fixed by installing an external waste gate). I cannot think of why this would be an issue on a N/A engine though.
Click to expand...

I alternatively have a N/A Mustang Cobra. I was researching headers and found that most of the supercharged guys had a 2-3/4 inlet setup whereas most of the N/A guys ran 2-5/8. Both setups ran into 3-3.5" collectors. Basically it was said that for a N/A application, there was no need for 2-34" headers and that it could actually have a negative effect on performance if going bigger on the N/A motor. Due to that, and something I read in a thread on here (will find the source) my speculation was that giving the 4Runner a more free flowing exhaust is good as long as it's not TOO free flowing. Kind of along the theory that performance wise, an exhaust isn't as efficient without an intake as it is with one and vice-versa.

If I am flat out wrong, I'll admit my fault. It's just what I have come to understand to to the nature of computer controlled EFI motors.
 
TrdLtly said:
Google "Exhaust Back Pressure good or bad"

As for your muffler idea: it would not be my first preference. I do a lot of highway driving. One of the great things about the T4R is how quiet it is inside. Wind noise, exhaust and intake all take away from that.

By the way, love the user name. Good idea.
Click to expand...

I'll Google that. I may have been too specific when Googling when I should have just stuck to the basics of performance.

Thanks for the compliment, I honestly just came up with it because I couldn't think of anything else.
 
wnelax04sr5 said:
intake will give you a good growl on the engine side, as for the exhaust, a flow master 40 or 44 will make it sound ricey, I've been in one with a super 44 and it was obnoxious at any speed. super 50 has had good results and has a more mellow and deeper tone.
Click to expand...

You sir, have a very nice build going on.
 
Okay update.

I confused back pressure with delta pressure. Back pressure bad, delta good. I think I'm good on that.

Anyone have thoughts on after market resonators or just forget them?
 
Exhaust Theory | NSX Prime

A pretty good, simple write-up of the exhaust system. Something simple to remember, a restrictive exhaust introduces resistance, which will require more work from the engine to push out the exhaust. On the other hand, an over-sized exhaust will allow the exhaust to cool. Cooler is denser (read: heavier), which will again require more work from the engine to push it out.
 
ret42 said:
Exhaust Theory | NSX Prime

A pretty good, simple write-up of the exhaust system. Something simple to remember, a restrictive exhaust introduces resistance, which will require more work from the engine to push out the exhaust. On the other hand, an over-sized exhaust will allow the exhaust to cool. Cooler is denser (read: heavier), which will again require more work from the engine to push it out.
Click to expand...

Thank you. That makes a lot of sense. I will read up on that.
 
I have the Gibson on mine its not loud but is louder than stock sound and has a nice low end growl. And I also noticed after installing that the engine felt like it wasn't held back as much as the stock exhaust made it feel.
 
404NotFound said:
Then, replace the stock resonator with the Flowmaster Hushpower 2 12" shorty, since it was designed as a resonator and my hope is that it would help with the potential drone.
Click to expand...

If you are wanting to keep the resonator, here is another option to look at.

QF/R Exhaust

A few years ago I had a 2004 Grand Cherokee that I had a Magnaflow muffler installed on. As soon as I took off from the exhaust shop, the drone around 2000 rpm drive me nuts. Later that day, I went back to the exhaust shop and had them make up one of these resonators. They thought I was crazy but did it anyway. It did take some adjustment with the length, but it worked really well.
 
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