Exhaust setup (Raptor headers, Xforce catback)

[Daytona]

Just thought I'd post an interesting thing I found last night.

I went back up to Auckland (from Tauranga) and decided to record the audio with the inserts out - and to be honest, sounded like crap. Exactly the same as with the inserts in (with an exception). But... played it back on the camera - sounded crap. I played the audio back on a laptop - sounded crap. Played it back on a home theatre system - sounded awesome. It's the one thing with recording audio - it doesn't sound 100% like it does in real life.

So I compared the two, with the insert and without.

Without the insert the exhaust is boomy and quite full of bass notes. When the car is under load and your accelerating, the boominess goes. But there are some notes of rasp, especially under the initial acceleration.

With the insert - no boominess. Sounds pretty quiet, no drone. Under load it's a very, very similar note to having no insert. But with one rather big difference. The exhaust sounds better. I didn't think it would, but when played back on a decent system, it sounds more high endish type of exhaust. Almost as if the insert "focuses" the audio - it's actually clearer and it removes 90% of the rasp.

Performance wise - still like a rocket. I'm concerned about the engine running lean, but the car won't get much action for a bit and then a tune will be done regardless.

Now it's slightly embarrassing - go through this entire process to get large pipes and you end up sticking a muffler insert in to reduce the flow. But I have been looking at different exhaust systems (a lot) and I have noticed a lot of exhaust systems get slimmer the closer you get to the rear. So what I'm attempting now is leaving the insert in, but altering the insert to allow more gases through, but keep the audio tight - if that makes sense.

I was a bit depressed last night before I compared the audio - was actually thinking if I should have left everything stock.

I was actually going to just live with the drone, but once I heard the actual exhaust sound change (ignoring the drone), it was like hearing the old 50's style radio broadcasts suddenly improve to high def quality. Like removing the impurities and noise, but keeping the good stuff.

The bonus - when I want open pipes - just take the insert out and probably keep two tunes - one with the insert, one without.

Note that this is a now a poor mans attempt at fixing the exhaust - I've exhausted my budget really, at least for half a year.
Anyone doing something similar, I would suggest following Tims advice!

[McDoof]

Thanks for that.
I had a bit of a rethink after reading Tim's last lot of posts too. He is running the full stock system with just the headers in there. That may just be the way to go. I really like the sound the headers bring, but I also like that the car is quiet when I am not thrashing it at the moment.

[Daytona]

Yeah man - make small changes. Just do the headers and see what it sounds like and if you're happy with it.
After having a few loud vehicles (mostly bikes) in the past, I now appreciate the quietness and power of the stock exhaust. It's not like Subaru are dum dums.

EDIT:
I did more tinkering and analyzing last night. It's actually really hard recording the exhaust of a vehicle, mainly because of the location of the mic. Having the mic 10 cm away from the pipe is not a true representation of the sound. I did a stationary recording this morning - and exhaust sounded different again (with the insert). I think the insert is going to stay to be honest - it makes the ride so much better for a daily driver and I'm pretty sure it doesn't affect flow that much (especially with the extra holes drilled in).

My partner - she gives me a bit of crap. She's saying well what did you expect with opening up the exhaust?!? Guess it way always an unknown - I knew it was going to sound different. Just a whole lot of learning and experimentation!

Anywho, I'm hogging this a bit too much - I've organized getting a cold air intake (used up the last of the budget with that), so when I fit that along with a tune, I'll get some audio/video clips up along with some photos.

[Daytona]

Quick video done this morning:
https://www.flickr.com/photos/tyron-d675/17238162472/

Has the insert in.

EDIT: and some photos from when the headers/cats/front y pipe went in:
https://www.facebook.com/pitstopgreenla ... 3741397598

It looks a bit different to that now, that's my car - first bit of work was done with Pitstop in Greenlane, work after that was done in Tauranga.
There are now two resonators in each branch of the Y pipe - stopped a lot (not all) of the rasp the high flow cats introduced. Where the flange is on the end of the Y pipe, that isn't there any more and the center pipe is welded to the Y pipe. Next time I've got the car on jacks will get some photos.

At the point of this photo, the car was stock from where the 3rd cat was to the back.

[McDoof]

Is that a Coby collector? I was looking into using one of those, but ended up just getting a pre made 2.25 in and out from Amazon. http://www.amazon.com/gp/product/B003IMOSHS
Perfect fit! The dual inlets match up with the stock pipes and means I can keep the stock flange on the mid section, just in case I ever feel like bolting on a catback. I think it is a little more restrictive due to being pressed rather than mandrel bent.

[Daytona]

Not 100% sure man - I gave Pitstop the headers and cats, but they did the collector. Wasn't listed as Coby on the invoice though.
The current resonators are Coby though (not pictured).

But everything did bolt up to the stock catback.
Good stuff on the collector being a perfect fit!

If I ever did everything all over again I would either (a) Raptor headers, everything else stock (b) true dual exhaust
Probably leaning towards (b) if I think about doing this exercise again.

[McDoof]

I think in order to keep it quiet I will be heading down path a)
Getting a set of Post FL GT mufflers to have a bit of a play with too. So I may look at opening them up and tinkering with the internals to get a bit of a deeper sound.

[Daytona]

I'm going to be having a good tinker on the weekend with the exhaust setup.

I've done heaps of analysis so far, just haven't posted the results online yet. Been doing recording of outside the car (mic 5cm away from exhaust), stationary mic, and recording inside the boot. Each time with the inserts and without, then trying in I mode compared with S# mode (S# mode produces more rasp without inserts). Time consuming stuff!

It's really difficult stuff to do by yourself and half of my issues only occur when the car has load.
I have a far better understanding (still needs to be better) of exhaust systems before I started, so I'm not complaining!

[McDoof]

You need one of these

[Daytona]

Interestingly enough, with my setup (headers, hf cats-100cpi, 2.5", resonators, xforce catback)

With no inserts, this is what I've found:
- drone around the 2500rpmish area.
- very bass like tones (analyzed audio, between 100 and 120ish hz seems to be the worst)
- drone is actually livable in either I, S or S#, it's not that bad.

With rasp - when the headers, highflow cats, front y pipe went in, the rasp was really, really bad. The 10" resonators in the front y pipe were installed to reduce this. Pretty sure caused by the high flow cats (would not recommend 100cpi cats).

Now, with no inserts, rasp is still there - but - it's not loud in the cabin, you can only hear it outside. And also - it's worse in S or S# mode. I mode it's hardly there.

With inserts
- hardly any drone at all
- performance seems largely unaffected when additional holes are drilled for more flow
- car is much quieter
- next to nill rasp
- exhaust is not as deep (but still on the deep side)

When I recorded the audio in the boot, the recording seemed to indicate that there was vibration (sounded like vibration), so that's the mission for the weekend. Inspect all parts to check for any vibration. There are heat shields above the mufflers that could vibrate due to the very low notes being produced by the exhaust now. I'd expect vibration to happen in either S# or I mode mind you.

Whew!

[Daytona]

Tried to do somewhat of a video.
Has 3 parts to the video:

- Inside with interior audio (note camera is behind a plastic housing, so it's a little louder than what you hear)
- Inside with exhaust audio. Mic is clipped onto licence plate.
- Stationary cam with launching the car, but not break neck acceleration.

Video:
https://www.flickr.com/photos/tyron-d675/17073674218/

I still think there is a bit of rasp, but going to try and have the partner drive it and I'll follow her and see what it sounds like.

This is with the insert in.
Anywho, hope this helps others!

[Daytona]

Annddd a picture of the exhaust:
https://www.flickr.com/photos/tyron-d675/17112485709/

If you flick through the gallery, there's a front shot of the car as well with the bonnet.

Made a bit of progress with the sound as well, just been modifying an insert to allow flow, but reduce rasp/drone and actually got somewhere with that. Just doing a bit of testing on it at the moment, but seems to have made a huge difference. It's not ideal, it's kinda patching the problem (rasp) and I'd rather have the problem fixed upstream (ie. mid muff) but this is a bit like a workaround until I can afford it.

[McDoof]

With the retune and the full exhaust are you seeing a major performance improvement?
Also what were you doing for the Cold Air intake? Something I would like to have a look at after the headers are done later this year.

[Daytona]

After headers:
- Performance was noticable after a tune

After catback:
- Performance felt reduced, almost too much flow.

After tune and catback
- Performance felt awesome.

I still think redoing the entire exhaust is overkill but it's what I've got and have to live with it.

As the car is right now, she feels great and def has great performance.
With the intake, current plans are to install myself next week, so by the end of the week should have something to report on.

[Daytona]

And intake in now
Just in the process of tuning. Pictures:

https://www.flickr.com/photos/tyron-d67 ... 199197870/

I'll put a post on the actual thread for the intake as well, just thought I'd update this one.
The intake diameter is HUGE!