Help on OP, FP, etc
 

Hey everything, still trying to learn more bout the bolt on stuff here.

Now I have a few questions.

I'm planning to upgrade to a ARK GriP and a UEL Header in the future, but I see some people running Over pipe (?), Front Pipe (?) and a few others. What do they do and what are the benefits/cons of swapping it out and why would one want to do it? I'm not trying to awake my neighbors or having the loudest exhaust or anything. I thought full cat exhaust replaces the whole unit up to the headers. Yes, I did google, youtube and search, but I might not be wording it correct.

Thanks!

Click on the Basic bolt on Mods link below

Make sure you get a quiet catback if your getting a catless header or front pipe else you will wake your neighbors :-)

It's my understanding that the exhaust system you are referring to includes the mid-pipe, mufflers and tail pipe. The header is the header.

You still have to move the exhaust from the header to the mid-pipe. This requires a front pipe and over pipe.

Also, it's my understanding that an aftermarket front and over pipes allow a free-er exhaust flow.


humfrz

I checked it out already, and all it says is just about little to no restrictions, Just want to understand why one would swap it out.

Ah okay, so pretty much it just opens up the flow and does nothing else correct? I want to make sure, see some people buy exhaust and get different Over-pip, front-pipe, mid-pipe, etc.

Thanks!

The stock overpipe is a couple of millimeters smaller than the header exit pipe.

The stock front pipe with cat is slightly restrictive.

If your after every last hp swap them out but gains fairly mild and the stock front pipe/cat keeps noise/rasp down well.

but the majority of benifit is gained from fitting a catless header by itself

Thanks for this info.

So If I'm getting a full cat exhaust system, I can run a Header that doesn't have a cat on it and still be okay correct?

If you run a catless header, your exhaust will be louder but fije with stock catback, or something like a invida Q300 catback.

Im not across all the emmissions laws everywhere but many only require one working cat in system.

If you swap out the frontpipe for catless or hi flow metalised cat in addition to a catless header exhaust will get louder and more raspy again. with aftermarket front pipes as well as carless header its going to be quite loud with anything but stock catback or a very quiet aftermarket catback.

The stock catback is not too bad restriction wise, but it may not give you a nice sound, but it will be quiet.

Ah that makes sense. Was planning on swapping to the Tomei UEL and ARK GriP exhaust system, and wanted to make sure it won't be a problem in CA and NV.

In California, you can not modify the catalytic converters in a vehicle and still pass emissions testing(visual in particular). I know this doesn't apply to ALL vehicles, but it most certainly does apply to ALL FR-S/BRZ. As the cat is an integrated component of the header, this means you effectively have no options for an upgraded header while still being compliant with emissions laws.

That said, swapping the header takes about an hour and our vehicles get a pass on emissions testing for 5 years after purchase date(maybe manufacture date, but I think purchase). I would take the enjoyment of the upgrades for 4-5 years and swap back when the time came.

But which will give you more "quietness"? Front pipe resonator or catted front pipe? Keep in mind i dont want rasp, but i can live with drine

Hard to say but the stock front pipe with ceramic cat is very good at cutting rasp and drone it also has what looks loke a helmholtz resonator at the rear of the pipe, the weird looking oval thing.
I think jdl and hks make resonated front pipes that are supposed to be quiet, but for sake of the planet and your ears its better to run a cat.

with either a high flow metalised cat or a resonated front pipe your going to need a quiet catbak or stock catback especially if its combined with a catless header.

many people make the mistake of getting say a perrin catback which sound great and are good quality catback by themselves, but add catless header and hi flow cat or catless front pipe and its way too loud and raspy\drony.

some people can put up with loud though

I heard the HKS one in person on a stock car, although it's pricey it's sounds quite good and is pretty close to stock sound level except for the tiny crackle and pops you may hear. It's probably quiet only because of the fact it has two resonators at the front near the overpipe and at the rear towards the midpipe.