Thannp

Hi all

Do you think by installing a H-pipe before secondary cat on a Dual to single to dual exhaust systemwill provide any benefits on an IS350?

Sound wise (deeper tone?)/performance wise?

Will it still utilize H-pipe benifit of increasing lowend TQ and better sound on this exhaust setup?

or it just adding weight

Any ideas?

Thanks!

MikeFig82

iTrader: (13)

I don't think so. I think it would be more beneficial on a true dual exhaust. The H pipe, or X pipe would be beneficial to that setup to equalize the banks pulses somewhat.

Thannp

Thank you. What about the sound? Will the tone change? Deeper maybe?

MikeFig82

iTrader: (13)

First a bigger engine will help. Then a better free flow of the exhaust would increment the sound to some degree.

CanadaL350

I was interested in this aswell.

Deleting 2nd cats and resonator and putting an H-Pipe in place for a true dual.

Unfortunately have not gotten it done yet. Debating between custom h pipe or just doing an axleback.

I know alot of V6 Mustang/American car guys do an h pipe to increase low end TQ and get a deeper tone.
However I'm not sure we would get the same result with our Japanese 3.5L V6

2013FSport

iTrader: (2)

Is this you car with headers, and does it still drone? If so, the H pipe would further reduce said drone. I don't think it will change the sound much if at all. My experience comes from 5.7 liter and 7.5 liter Ford V8's. But neither were known for drown, perhaps because the mufflers were shortly after the true dual exhaust H pipe and the tail pipes were slightly smaller than pipes forward of them to keep heat and velocity up.

Thannp

It should work great on a true dual setup. But I am wondering if it will give the same benifit when fitted on a dual to single to dual set up.

Thannp

Yes, I have PPE header fitted in my car. It doesnt drone much because I had hemholtz tube installed but can still notice slightly at around 2500-2800rpm. If H-pipe can reduce some drone. I should give it a try

CanadaL350

Not a 2-1-2.... I would delete 2nd cats and resonator and replace with a straight H pipe all the way back to OEM mufflers.

Thus making a true dual setup. I don't think it would be worth it on a 2-1-2.

AMIRZA786

It looks like he has custom Branch resonators, that would take care of a lot of the drone

2013FSport

iTrader: (2)

It will help equalize the sound waves.
Does it still have resonator? People ditch them and end up with a raspy drone as that is their purpose in life is to absorb the sound reflection just as the old muffler did back in the day before they moved them to the tail end of the car.

I have yet to find documented evidence on why they did this but suspect it is emission related. The goal being keep the exhaust gasses as hot as possible as long as possible. Mufflers and bends drop velocity and heat. Having the mufflers near the trans reduces both. That said, that setup never had drone issues like modern cars do.

I'm tempted to try it one day. As in, a crossover, into mufflers where the resonator is now, then nothing but a tailpipe to the rear of the car with pretty tips on it.

Thannp

yes, it still have resonator but not stock. All my exhaust system is in stock configuration but all of the pipe has been replaced with custom frabication work.

PPE header---2.5inch pipe with branch resonator-----manaflow cat-----surugaspeed resonator------ surugaspeed twinloop exhaust

Just looking to take it up a knotch without going true Dual.

AMIRZA786

I'm curious how well branch resonators work as compared to stock.Stock, there is zero drone, I've always had issues with drone with aftermarket resonators. Case in point, I had a 2018 Civic Si, decided to install an aFe Takeda CAT Back stainless steel performance exhaust (mistake number 1), it sounded much more aggressive than stock, but the sound got old really fast and droned like crazy on the hwy. I didn't have any place to store the stock exhaust so I sold it (mistake number 2), so I couldn't go back. I then took it to a muffler shop who suggested a baffled glasspack, that toned down the sound a little but did almost nothing for the drone. I then bought and installed a Vibrant Ultra quiet 3" resonator, it brought the drone down maybe 50 percent, but never eliminated it. Whenever I had passengers, they would make comments like "it sounds like a sports car"...translation: your car is too loud. My wife would comment it gave her a headache. Lesson learned

Thannp

If you get the calculation right it will work very well. You need to know what frequency you want to cut then you make the branch resonator to target that frequency accordingly.

For my case it make the drone almost unnoticeable. Only a little bit left that I can live with.

Also the branch resonator do nothing to the sound of your exhaust. It will stay as aggressive as it did before you install the branch resonator.

Highly recommend

Thannp

while I was having some lastweek. I had a chance to try the setup out.

Here are my findings

Pro
1.) It make your low end sound better. More meat. Provide a fuller sound at idle and light throttle application
2.) It does improve lowend TQ. Noticeable improvement
3.) it does reduce my drone further

Con (Big one)
1.)When you use half throttle on a high gear. Eg. Trying to overtake someone without wanting to shift to a lower gear. The car will lose power at around 2000-2500rpm. It will feel like the engine is starving for fuel. Engine sounds different. But once rev thru 2500rpm the power resumes normally.
I did not find any issue on other throttle applications. Free reving/at load/WOT or gentle throttle. The car runs perfectlly with more grunt at the lowend

2.)no noticible improvements on the top end


At first I didnt think that a H-pipe could cause this. So I went on trying to identify the problem without thinking that the pipe is what causing it. I visited my tuner friend who tuned my car for E85. We took it for a test drive with a data logger and we found out that the engine does run lean when in bogg down between 2000-2500 rpm. And we also found that this is the area when the ecu shift the injector from using port injector alone or twin injector or to direct injector only. Depending on the load request that the ecu recieves. He the custom wrote another map incresing fuel during light load hoping to fix the problem.

But the problem is still there so I am thinking it could be my injectors are on its way out because I am running E85. So I replaced both upper and lower injector with a spare set I have.

Still no go. Problem still there. I was lost haha. I know for sure that the Direct injector provide sufficient fuel because the AF ratio looks perfect at WOT

My firend were saying you need a bigger port injector bla bla.

Finding a bigger port injector will be hard. The upper injector from ISF look similar but I dont think anyone knows how much it flow.

so I decide to reverse my engineering. I had a set of Invidia midpipe in my garage so I installed them back on the car.

And Voila! Power lost is gone.

DAMMIT HAHAHA. still dont know why a H-pipe could cause this on a 2-1-2 system. Maybe too much back pressure? Airturbulance?

There you have it. Hope it help you in some way.