Quiet exhaust mods for max performance gain

Posts specific to the 3.0 litre NA H6 engine

Quiet exhaust mods for max performance gain

Postby B Spec'd » Sat Sep 09, 2017 7:42 pm

I have only recently joined the forum but have been lurking for a while.

I have had my '06 H6 Spec b for a couple of years and have had enough of the low end lack of power.

After much reading through topics I have decided to get a tune and a set of Raptor headers to wring a bit more out of her.

I want however to keep her quiet and stealthy as much as possible. Most of the exhaust posts i have found talk of full system replacements or at least hi flow cats and cat back systems.

I want to keep as much stock as i can while still getting benifit of the headers and tune.

So my question:

What exhaust components should i change to make the most of the headers and tune while sounding as close to stock as possible?

Any advice and opinions apreciated!

Cheers
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Re: Quiet exhaust mods for max performance gain

Postby edenotto9 » Sun Sep 10, 2017 7:44 pm

From what I've heard about raptor headers they are definitely a step in the right direction in achieving your goal. Deleting the 3rd catalytic converter with a 2 into 1 pipe or (as i plan on doing) replacing it with a resonator to keep it even quieter, would be the next logical step i believe, should give some nice gains.

I would probably just leave it after that, just headers and 3rd cat delete, that will maximise performance gains without increasing the noise much at all, basically as long as you keep the catback stock (stock centre resonator and mufflers) then it shouldnt be too much louder than stock.
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Re: Quiet exhaust mods for max performance gain

Postby B Spec'd » Thu Sep 28, 2017 8:42 pm

edenotto9 wrote:From what I've heard about raptor headers they are definitely a step in the right direction in achieving your goal. Deleting the 3rd catalytic converter with a 2 into 1 pipe or (as i plan on doing) replacing it with a resonator to keep it even quieter, would be the next logical step i believe, should give some nice gains.

I would probably just leave it after that, just headers and 3rd cat delete, that will maximise performance gains without increasing the noise much at all, basically as long as you keep the catback stock (stock centre resonator and mufflers) then it shouldnt be too much louder than stock.


So you reckon third cat delete rather than replacing front cats with hiflow units? if im changing out headers im worried about reducing gains from restrictive cats if i dont swap them out...

Have you had a tune yet?
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Re: Quiet exhaust mods for max performance gain

Postby edenotto9 » Sat Sep 30, 2017 6:38 pm

B Spec'd wrote:
edenotto9 wrote:From what I've heard about raptor headers they are definitely a step in the right direction in achieving your goal. Deleting the 3rd catalytic converter with a 2 into 1 pipe or (as i plan on doing) replacing it with a resonator to keep it even quieter, would be the next logical step i believe, should give some nice gains.

I would probably just leave it after that, just headers and 3rd cat delete, that will maximise performance gains without increasing the noise much at all, basically as long as you keep the catback stock (stock centre resonator and mufflers) then it shouldnt be too much louder than stock.


So you reckon third cat delete rather than replacing front cats with hiflow units? if im changing out headers im worried about reducing gains from restrictive cats if i dont swap them out...

Have you had a tune yet?


No havent had a tune yet, waiting on the headers before i do that. Definitely do the 3rd cat delete, its cheap and easy to replace with no down sides, just get a pipe made, from what ive heard its usually about $100.

Ive heard conflicting things about front highflow cats, some say they are unnecessary, pretty sure i read a post from 'Tradewind' (Guy who designed the headers) somewhere on here saying that they are pretty gimmicky and not really needed unless going supercharged. Whilst others would argue that they are worth it. With the headers some chose to go with them, some chose to stay stock, although if you want to maximise gains its probably a good idea.
That said they will definitely change the sound, they will make the exhaust a lot raspier, although an extra muffler/resonator, perhaps in place of the 3rd cat, will help cut back on it.
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Re: Quiet exhaust mods for max performance gain

Postby edenotto9 » Sat Sep 30, 2017 6:42 pm

B Spec'd wrote:
edenotto9 wrote:From what I've heard about raptor headers they are definitely a step in the right direction in achieving your goal. Deleting the 3rd catalytic converter with a 2 into 1 pipe or (as i plan on doing) replacing it with a resonator to keep it even quieter, would be the next logical step i believe, should give some nice gains.

I would probably just leave it after that, just headers and 3rd cat delete, that will maximise performance gains without increasing the noise much at all, basically as long as you keep the catback stock (stock centre resonator and mufflers) then it shouldnt be too much louder than stock.


So you reckon third cat delete rather than replacing front cats with hiflow units? if im changing out headers im worried about reducing gains from restrictive cats if i dont swap them out...

Have you had a tune yet?


Ok i found it

"As you can see the difference in the power at 7300rpm even with stock cats - this proves well enough changing cats on NA would be useless to do. Its just 110kw stock and around 137kw with the headers, you cannot expect any gain larger than that on an NA 3.0 liter, even I was shocked - you get those kinds of gains on a V8 5.0 liter - if you are lucky, to see it on a 3.0 was amazing. Of course you can see the torque curve is very enhanced, more torque everywhere in the working rpm range"

viewtopic.php?f=16&t=21723&start=30

scroll down that page to 'tradewinds' post, check out the dyno graph if you are worried about power loss
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Re: Quiet exhaust mods for max performance gain

Postby dan_ashcroft » Sun Oct 01, 2017 9:16 pm

I have Raptor headers running into 2 x 2.5" 200 cell Magnaflow cats, merging into 2.5" pipe that runs into a 2.5" Magnaflow centre muffler, and 2.5" piping to the rear muffler, which is a single Ultrex muffler. It can be quiet at low throttle / low rpm situations, but is not quiet when putting out power, especially above 4k. Sounds beautiful though.

I think it could be slightly quieter with a different rear muffler, the Ultrex twin-tip looks big, but up to a third of the muffler is non-active as it splits into two within the muffler and this area is all un-muffled. Might swap to another Magnaflow or something else in the future.

Not really a direct answer to your question, but gives you an idea what you will get if you head down my route.

Re the cats, my gut feeling is you would notice an improvement with high flow cats over stock, but this would come at the expense (for you) of more noise. I don't have any evidence to back that up though as I got the headers and cats done at the same time so can't separate the improvement each item had...
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Re: Quiet exhaust mods for max performance gain

Postby Tradewind » Fri Nov 24, 2017 6:42 am

Just go the Raptor Performance headers if you want quiet and good performance - obviously with a KiDo Tune/ Matt Mcleod
2015 Liberty 3.6R (6GEN) - Raptor headers and Raptor SUPER MAF
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Re: Quiet exhaust mods for max performance gain

Postby vicious_fishes » Mon Nov 27, 2017 3:55 pm

I've recently put an my16 sti catback system (requires some custom fab, but physically fits) onto my gen 4 and I cannot get over the difference it has made. The difference in smoothness/running of the engine is incredible. Power is noticeably up too.

It's only just, JUST louder than stock. Not enough to notice when driving, only noticeable when idling or at high rpm. I can't recommend new gen sti or just tuned by sti exhausts enough, I had no idea just how restrictive the OEM exhaust was until adding this.

Once the raptor headers are installed and a proper front section fabbed, I anticipate the difference to be even more substantial.
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