stock centre muffler restriction H6?

[Brunsy3.0]

Hey All

I am considering adding to my partly upgraded exhaust as currently I have raptor H6 headers 3rd cat delete and phat quad tip s/s mufflers
I am looking at 200cel cats and possibly the xforce centre and y pipe but am quite hesitant just to bolt it on as the x force muffler can be quite droney

I have heard from a muffler shop that the stock centre pipe muffler is not overly restricting he also compared it to a forester muffler
I dont have much of an idea on this type of thing and am just looking for some advice

Also with cats do brands matter as with most things for better quality ive heard only jap cats are decent but dont know much about it,
for example....the diameter of the cat and pipe to go from headers to the cats and then from cats into 2 to 1 then to centre pipe

Any advice is appreciated

Cheers

Brunsy

[Brunsy3.0]

Any ideas anyone?

[RX25SE]

I'm going to fiddle with mine when the headers arrive.

I looked at the center resonator and a piece of wire will pass all the way through so I suspect it only has perforated tube so there is no restriction.
I'm going to leave it in place as I think it will drone too much without it. Between it and the cats, they do a good job of muffling the noise as the car is surprisingly quiet if you go for a drive with the rear mufflers removed, just sounds odd.

[Brunsy3.0]

What are your other exhaust plans apart from headers?

[RX25SE]

What are your other exhaust plans apart from headers?

I may fit a smaller (shorter) center resonator as I have a spare center section but I'll see how it goes with the headers on.
I will however do as you have done and delete the 3rd cat when fitting the headers.



Did you notice a big change with your current exhaust mods?

[Robbks]

there's thread here somewhere showing one cut apart
it's a straight through perforated tube
so next to no restriction.
the CAT's are the restriction

[Brunsy3.0]

I got quite a bit more power even before the tune I have a graph somewhere but after tuning the headers in it scares the misses especially after driving the hilux around haha

I am now really keen to get an xforce centre and y pipe and jam the stock resonator into it should tone things down aswell as open it up a bit. Ive been thinking magnaflow 200cpi cats but not sold on that idea yet
Apparently the H6 may lose some down low grunt which could possibly make town driving a pain

[nhimsta]

Hey mate I have fitted the xforce exhaust ,left the resonator out and will bolt up to 200cell oval magnaflow high flow cats andn raptor headers when the arrive .
The sound of the exhaust has taken a week to bed In.... And sounds nice and smooth and powerful.
...quote "like a rocket" ....after a tune once all installed headers and cats .....
I can take a vid if you would like to hear the sound ..

[Brunsy3.0]

Yeah mate that'd be great. Always good to hear first person perspective on these matters. My main concern in drone especially around the 3000rpm mark as 130kmph is around that area and when cruisin on the highway I dont want my head to explode from frustration
have heard that the x force centre muffler is quite tinny and droney so am seeking advice to keep the performance flow strong but dull the unwanted noise from the system

If at cruise I can get the drone and noise to a minimal level id be stoked but on WOT the more noise the merrier haha

[BATMAN87]

Any of you guys notice better performance by just deleting your 3rd cat? And how much more loader did it get.

I have tcp quads on my outback, and I’m a little concerned if I get rid of the cat that its gona get way too droney as its an auto.

[Robbks]

I noticed a little more smoothness at low throttle after deleting the 3rd cat,
but not a huge amount

[Brunsy3.0]

No more drone I wouldnt think. I got headers 3rd cat delete and phat quads and sounds sweet at wot im looking to liven it up a bit with x force catback rewelding the stock centre resonator back in to eliminate drone but am time and money poor atm

[BATMAN87]

yeh sweet,
cheers guys. i'll give it a go, hopefully this weekend

[dr20t]

I will go as far as to say your centre muffler will be improving performance on a h6, specifically in the mid range torque.

As would the third cat (not the first two in/ near headers as these would restrict engine Venturi)

N/a is different to turbo. You will want some back pressure to assist with scavenging. Anyone telling you a hi-flow cat will improve overall performance on anything but a wild h6 n/a engine is flogging it

As rob said though, you will probably notice better throttle response and top end power may improve slightly due to increased flow but my money is on you losing mid range torque with an otherwise stock engine setup.

My 2c

Mick

[Out6ack]

The center muffler is fiberglass packed yeah??
Back when racing dirt bikes, we re-packed the fiberglass in our straight through muffler to lower noise levels. This was before fuel injection in dirt bikes, so the gases were nowhere near as clean as our cars.
But still, after 160,000km, im guessing the fiberglass in my center muffler would be clogged and ineffective. Has anyone dissected one with a heap of kays on it to confirm this? I'm not considering re-packing it, rather replacing it with 2 x 12" hotdogs in-line. I actually just got a 12" hotdog installed after the center muff and it gave a deeper note and removed some raspiness. A good improvement.

20140616_152237.jpeg (91.23 KiB) Viewed 3480 times

The bit I'm trying to get my head around, is having another two installed - 3 feet of hotdog muffler as my center section! A traditional sports muff wont fit.
My system is: SS Raptors, 100cel bokka cats, 3rd delete, 12" hotdog after mid muff, stock rear muffs (until I find some used Phat/TCP quads).
I want to retain back pressure as per Mick's post above, but if stock mid muff is straight through with clogged glass anyway, I'm guessing another 24" of fresh fiberglass would only help this.
My aim is to get a much deeper note from the system. Deep as possible. As cheap as possible! Money's tight and I can do this for under $200...
Noise level now is ok, but still too raspy.
Anyone done this??