midbox/bullet selection

[Veloc]

Dear fellow forumers,

I was wondering, if someone can enlighten me on the selection of midbox or centre bullet. Let's say it's a manual car and the whole exhaust setup is already optimum except for the midbox. What type of bullet/midbox is more for:

1. Acceleration/pickup
2. Top speed
3. Low end - midrange torque
4. Top end power
5. Silent ride

Thank you!

 

[vr2turbo]

As far as I know, is the whole exhaust system set up and not only the mid box. Extractor, size of piping, rear muffler, engine power and torque, manual or auto all plays a part....

 

[Veloc]

Let's say everything else is set up right. Just want to know about the bullet because it is the limiting part now. Anyways thank for the reminder, I amend the original post.

4AGE 20 valve Blacktop manual.
4-2-1 extractor
2.3" piping
S-flow muffler 2.5" size. Less than ideal but going to change back to 2.2-2.3".

 

[6UE5t]

To me it doesn't make much difference coz mid silencers are mostly straight flow anyway. So the decision is not so much about performance but more about sound filtering, how loud or how silent you want. If you want it loud then just don't use at all or use short ones, if you want more silent then use longer ones.

Btw there are mid boxes that have like a rotating/twirling pattern of holes inside it. I've never used those kind so not sure how it's like.

 

[ken yeang]

without a midbox, the car will be exceptionally loud. Power/performance wise, can say much.....
My neighbor's son had his car's mid box removed. Now, everyone in the neighborhood know when his son come home at night....

 

[vr2turbo]

To me it doesn't make much difference coz mid silencers are mostly straight flow anyway. So the decision is not so much about performance but more about sound filtering, how loud or how silent you want. If you want it loud then just don't use at all or use short ones, if you want more silent then use longer ones.

Btw there are mid boxes that have like a rotating/twirling pattern of holes inside it. I've never used those kind so not sure how it's like.

Most I saw got the holes pattern, suppose to slow the out going exhaust gas....

---------- Post added at 07:30 PM ---------- 6 hour anti-bump limit - Previous post was at 07:29 PM ----------

To me it doesn't make much difference coz mid silencers are mostly straight flow anyway. So the decision is not so much about performance but more about sound filtering, how loud or how silent you want. If you want it loud then just don't use at all or use short ones, if you want more silent then use longer ones.

Btw there are mid boxes that have like a rotating/twirling pattern of holes inside it. I've never used those kind so not sure how it's like.

My VR same same, direct to rear one straight through box only, not even S....

 

[6UE5t]

Most I saw got the holes pattern, suppose to slow the out going exhaust gas....

---------- Post added at 07:30 PM ---------- 6 hour anti-bump limit - Previous post was at 07:29 PM ----------



My VR same same, direct to rear one straight through box only, not even S....

Mine one just 1 long mid silencer then a pair of straight flow twin loop mufflers at the rear.

 

[vr2turbo]

Mine one just 1 long mid silencer then a pair of straight flow twin loop mufflers at the rear.

But I am sure the mid have swirl hole in them, if not it is just the same as a long pipe.....lol
By slowing down the air flow helps quiet it down too...

 

[6UE5t]

But I am sure the mid have swirl hole in them, if not it is just the same as a long pipe.....lol
By slowing down the air flow helps quiet it down too...

There was a youtube clip from Magnaflow telling that not necessarily a straight pipe flows faster than one with a straight through silencer. His reasoning was that the air can actually travel faster by having less friction (due to less metal material caused by having the holes inside the silencer) compared to full friction of the metal on a straight pipe. Not sure how true is that, can be just a marketing trick/gimmick to get people to buy their silencers.

 

[^pomen_GTR^]

There was a youtube clip from Magnaflow telling that not necessarily a straight pipe flows faster than one with a straight through silencer. His reasoning was that the air can actually travel faster by having less friction (due to less metal material caused by having the holes inside the silencer) compared to full friction of the metal on a straight pipe. Not sure how true is that, can be just a marketing trick/gimmick to get people to buy their silencers.

actually less silencer the better for power...

but with most people do it wrong when upsizing the piping size too much....


because usually most manufacturer use just small enough piping size for better driveability balance.....instead of full power....


so if me....i'll delete all silencer and retain stock piping size with whole new straight-er route pipe setup....or just go one step bigger overall pipe size with 1 matching size rear straight type silencer(with no center bullet/silencer)....

 

[6UE5t]

actually less silencer the better for power...

but with most people do it wrong when upsizing the piping size too much....


because usually most manufacturer use just small enough piping size for better driveability balance.....instead of full power....


so if me....i'll delete all silencer and retain stock piping size with whole new straight-er route pipe setup....or just go one step bigger overall pipe size with 1 matching size rear straight type silencer(with no center bullet/silencer)....

For me I still keep my mid silencer coz it'll be too loud without it for a daily driver car like mine.

 

[Veloc]

For me, I want silent (due to aging) so removing any midbox is out of choice. I am just trying to look for the most suitable type of bullet/midbox for optimum performance. Some say use a larger body midbox, some say use a flow diameter midbox, some say use the same diameter as original piping, some say use a bullet.

I just want to know which type of bullet give what effects in terms of acceleration, top speed, silencing....

 

[^pomen_GTR^]

For me, I want silent (due to aging) so removing any midbox is out of choice. I am just trying to look for the most suitable type of bullet/midbox for optimum performance. Some say use a larger body midbox, some say use a flow diameter midbox, some say use the same diameter as original piping, some say use a bullet.

I just want to know which type of bullet give what effects in terms of acceleration, top speed, silencing....

For me I still keep my mid silencer coz it'll be too loud without it for a daily driver car like mine.

i'm using FGK legalis super R on my scooby which is really2 quiet compared to many prang2 vtec on the street...

heck even with straight pipe with just rear muffler, my scooby too silent compared to other fellow scooby using those many other high performance rear muffler....

 

[vr2turbo]

For me, I want silent (due to aging) so removing any midbox is out of choice. I am just trying to look for the most suitable type of bullet/midbox for optimum performance. Some say use a larger body midbox, some say use a flow diameter midbox, some say use the same diameter as original piping, some say use a bullet.

I just want to know which type of bullet give what effects in terms of acceleration, top speed, silencing....

Acceleration need some form of back pressure, top speed best no block straight out, so there are pros and cons. Best is well tuned, get best of both worlds.....

 

[Izso]

bro-fellow-old-man-Veloc ( )

The midbox generally is there to just silent the exhaust. The Caucasians call it the 'resonator'. Generally it's recommended to maintain the piping size and get a straight flow design and generally the bigger the midbox the quieter your exhaust. If you have a look at Magnaflows website, they have a type of straight flow exhaust 'box' that doesn't slow down the flow of exhaust but quietens the exhaust at the same time. In fact it somehow speeds up the flow of exhaust. But since you have a S-flow muffler at the end, just get the straight flow with the largest size canister your car can fit without downsizing the piping size. If you're gonna swap to 2.3" then suggest you add the resonator only after you change to 2.3" throughout the setup. Generally speaking though. 0.2" difference shouldn't make too much of a difference I think?

Those twisters or whatever add a lot of back pressure to the setup. You already have a S-Flow and yours is a manual, so don't get those bullets or whatever. Don't waste your money.

Personally, without knowing what type of s-flow you're using (baffled or mandrel twisted or recirculated or just 90 degree bends) I'm going to assume ideal s-flow. Usually the biggest impacting parts of your exhaust is the headers, catcon and rear muffler. Get a decent 4-1 extractor and heat shield it or titanium wrap it (fibreglass is hard to work with) or ceramic coat it, get a high flow catcon (save the planet mah) and fit a good fitting sized pipe mandrel bent throughout. A large middle resonator (straight flow) and a decent s-flow muffler should by right give you a decent rumble but without the drone at higher revs. My old Wiras setup was like that. Idle had that pretty nice rumble and acceleration had a loud rumble then it went quiet when cruising at 3.5k rpm. Was somewhat louder when redlining but then again what doesn't make noise at those sort of rpms?

Ideally though, you'd probably do well to pay hard money to get a professional to properly calculate the length of exhaust, diameter, type of extractor, etc. I haven't seen any shop do these sort of calculations and have only ever seen it done in race cars.