HiPatrick

I'm looking to replace my current custom built exhaust. After having it for two years, I have had enough of the exaggerated V8 sound and added drone. I feel as if there is no point driving a car like this, with a loud exhaust that is.

I am struggling to source a factory exhaust locally in Australia, and I don't want to pay quadruple with the shipping fees from Japan, so I was thinking.. should I just get a muffler shop to replicate the exhaust (minus the two back catalytic converters) ? Would I notice much of a difference to the original factory exhaust? Once it's quiet, it'd be a breathe of fresh air to what it is now. Basically I would need the two mufflers, the resonator Y-pipe, and a third catalytic converter (the small cat), something on the lines of that.

BigBoomer

There are only 3 CATs. One bolted to each header and one where the Y-pipe joins the 2 banks together.
The 2 cylinders after the 3rd CAT are the Resonators and are what is mostly responsible for reducing that booming/droning sound.
After that there are the mufflers which further reduce the overall noise level.
You should be able to get a set of resonators from a recyclers and then have some mufflers fitted after them to quieten her down.

AVSRacing

What is your current set up? I've always wanted to try this but can you just get your shop to weld up a j pipe or Helmholtz tubes? Apparently they work to get rid of drone. Or you can always add resonators in-between and leave the mufflers you have.

HiPatrick

About two hours away from me there's a wrecker that has the exhaust, though I think the third cat is not attached to the exhaust that he offered to sell me. It has the Y-Pipe and muffler boxes attached only. Does the third cat drastically increase sound if removed? Any other option to consider? Or should I be looking around for that third cat as well.

HiPatrick

I have "sports" style mufflers (hotdog resonators), deleted Y-Pipe resonators, 2.25" X-Pipe installed and third-catalytic converter (before the sensors) removed, also using angle cut chrome exhaust tips. Sound is loud and rumbly deep, drone is present around 2000 rpms, tone is smooth with minimal rasp. It really has a distinctive note as compared to the more common American V8 engines. I prefer to revert back to the factory exhaust, as I want the car as quiet as possible now, especially because I will be entering a shift work phase again and I dread starting the car at 9.30 PM.

AVSRacing

Yea then I guess the cheapest option is to find a set of used mufflers, y pipe. I don't think the third cat will make much difference as long a you still have OEM Res and muffler. The third cat looks pretty small anyways. You can always weld in another resonator mini muffler in that area if it's not quiet enough. But that set up with no 3 cat should be pretty close to stock. Maybe YouTube 3 cat delete.

BigBoomer

Since a CAT is a honeycomb matrix it will reduce overall noise level somewhat but it is designed for gas flow, not noise reduction, so I would imagine you can do without the 3rd CAT if you don't have emissions testing in your area. Here in the UK it would fail the annual emissions test if that 3rd CAT were removed.
With the factory resonators and some half decent aftermarket mufflers it should sound quite decent but if you want the factory (lack of :-) ) noise level, then you need complete the factory exhaust system.

josheddie33

Which model Borla ProXS did you put on?