Full exhaust system question. ( HIGH FLOW CAT)

[DollarBill]

ok so i just recently purchased a tanabe concept G axel back exhaust. And i also just ordered a gloss black injen CAI and waiting for it to get here so i can put it on. now i dont plan on putting a turbo or super charger in my car cause its a daily driver and i dont think i need it. however i do wanna do a full exhaust system and pullys, my question is. after i get headers and my S pipe is it worth getting a high flow cat? since i live in PA and i wont pass inspection with out a cat i gotta keep mine. ive been reading an it seems like everyone is saying high flow cats are kinda pointless?? just curious if anyone has one or experience with one and had any tips? or other suggestions i could do would really help. still new to the whole tuning thing but learning fast

Next part im buying is my s pipe only cause its cheap but ill have to wait to get headers cause im tight on money atm and im gonna have to have my exhaust shop custom bend me a pipe from cat to my exhaust so if a high flow cat is worth it ill buy that as well then have everything done at once.

[CadenceScion]

OEM CAT's are restrictive, a high flow CAT will be less restrictive and more free flowing. If it was me I would get one.

[DollarBill]

do i have really any other options?

[Mengsta]

If you want to keep your cat, then a high flow cat is probably your only option. Other than that, you could just purchase a cat-less midpipe, the Megan midpipe for example, and just reinstall the factory midpipe when it is inspection time. You stated that you wanted a Megan header, that header will remove your primary cat that is on your OEM header, so I think that might have something to do with inspection anyway. We have these items in stock btw =].

[c500129]

if you are worried about it and need it to pass inspection where you live then go with the hi-flow cat.

[CadenceScion]

You can get High-Flow CAT's from CatCo and Magnaflow.

[connman429]

Believe it or not, you will actually see more of an increase with a hi-flow cat than you will with the header. If you pull the heatshield, you will notice that the tC actually has a header already. That's part of the reason you will only notice a 1 or 2 hp increase with an aftermarket header swap.

[xlxhockeyxlx]

i thought weaponR was about 10WHP more. Also, i was thinking about a high flow cat. Will this hurt my performance with an aftermarket header? or is it negligible 1WHP

[navylife59]

To better understand the subject about catalytic converters and why most modern cars (gasolina), read this Tech Article.

http://www.club-tc.com/forums/tc-kno...nsors-mil.html

For the complete exhaust.

http://www.club-tc.com/forums/tc-kno...omponents.html

Removal of the OEM header will also delete the primary TWC. The primaries go directly into the collector which is where the Bank1Sensor1 wideband AF/R is located. The secondary TWC is in the beginning of the mid-pipe just after the s-pipe which houses the Bank1Sensor2 Heated narrowband O2 sensor.

A high flow cat replacement is not the cure all for passing emissions. The ECM tunes directly off the primary TWC and only uses the secondary TWC for fine tuning and fault checking. There is no guarantee of passing an emissions test with only a secondary cat, even if, it is the OEM one. High flow (metal core) cats are not as efficient as ceramic core cats so that would most likely fail a stringent (Cali) exhaust analysis.


Aftermarket ZPI mid-pipe laying ontop of OEM for comparison. OEM is roughly 2.25" ID and the ZPI is a full 2.50" ID. Notice that the OEM is fairly straight. The long barrel in the front is the OEM resonator and the smaller barrel in the back is the secondary cat.


A quick look at the primary TWC in the collector of the OEM header. Megan Racing's header originally came with a cat installed but it was of cheap quality and would break apart and clog up the OEM cat in the mid-pipe. All aftermarket cats today (for the tC) are cat-less. There will be an appreciable gain in torque/HP and mid to high powerband. The next restrictive is the s-pipe as it has many tight bends that are not mandrel bent so these bends actual have a much reduced ID. The aftermarket axle-backs offer the least amount of real world power increase. Remember, this is with the ECM doing all the number crunching. An aftermarket tune, like with the UniChip piggyback can increase peak power gains.

Resonator 1.0.JPG
This is my cat-less mid-pipe (done by Jotech) as part of my complete custom exhaust.
Notice that it has only one 24" resonator. I actually have a 2nd 24" one installed just after and a custom made silencer/resonator tip in the axle-back.

Megan S-pipe2.JPG
Proof of Megan Racing products poor quality and design. Steer clear of their stuff.