2017 Front Pipe questions
 

I've been searching through the forum and can see people confused and saying different things about whether or not the front pipe (2nd cat) is compatible between the 2017 and pre-2017 86 models?

I've bought a used 2017 which is in perfect condition apart from the 2nd cat having a really slight hit from a speed hump. I could leave it as is but every now and then I hear a slight rattle obviously from the cat having some loose material inside. (image attached)

I'm thinking of either replacing it with a stock pre-2017 version I can get from a local wrecker (from a car that had done 30k kms) or pick up an aftermarket front pipe.

My two questions are: are 2017 models compatible with pre-2017 front pipes? Also if I go aftermarket (something like this: https://www.mrcperformance.com.au/ve...-brz-high-flow) will it throw engine check codes since the cat has changed? I'm guessing not as there's no o2 sensor on the secondary cat?

Thanks!

Yuup front pipes are identical only the axle back portion (muffler) the flange has changed, thats the only difference between the pre-2017 and the post-2017

No CEL, secondary cat is not monitored Only the header cat is monitored.

if you are going through the trouble why not put a nice high flow cat on there

Yea if it doesn't require a tune I probably will do that. The only other thing I'm concerned about is if a high flow cat without a resonator would cause much drone on the highway? The stock unit has the cat and resonator built in and most (if not all) catted aftermarket pipes seem to not have a resonator.

Not sure what you can get in the AUS but JDL makes a catted/resonated fp. And I have Hooker Blackheart catted/Helmholtz resonated fp on my setup.


http://www.ft86speedfactory.com/hook...E#.XC6yA2cUnX4

Surprisingly the shipping from there to AU isn't too bad for such a large item. Although i'd definitely be hit with import taxes :/

Damage looks like superficial heat shield damage only. Are you sure the noise is broken cat pieces and not something else like a loosened fastener?

Just knock out the cat if it's rattling.

No cost (bar gaskets), and no codes.

I had it hoisted up and we gave everything back from there a check and nothing was loose. I gave the cat a knock and heard a very slight rattle from it which would be amplified by the pressures of the exhaust which is why I'm confident it must be a very, very minor amount of internal damage caused by the knock.

I actually just picked up the car second hand (2017 model with 23k kms) and by law in Australia it has a 3 month used car dealer warranty on top of the new car warranty. I'm going to take it in so they can have a look and perhaps replace it.

Mate, you have no idea how tempted I am to do that. I've had three cars which ever developed issues in my life and all three were cats failing. I hate the things!

How do you like that front pipe? Haven't heard too much about it. Thinking to swap out my stock front pipe since my catback produces a lot of drone, and this one seems like a good choice since it has a built-in Helmholtz resonator.

I would just remove that heat shield. Those are common sources of rattle noises on Subarus, especially at higher mileage. See if that fixes it before you go spending money.

Yes the J-pipe/Helmholtz resonators are good for cancelling out frequencies/drone at a certain rpm range.


I changed both that and Borla exhaust at the same time as setting up my Ace 350 so its hard to say which component did the most but drone is minimal and civil for having an opened up exhaust


Id choose between the Hooker FP or JDL catted/resonated if you have a catless header. I don't think just a high flow cat is enough for noise suppression unless you like being obnoxiously loud in a fairly slow car.


For the OP I would also check the overpipe which has shielding that can rattle as well in the same area