Frontpipe & Overpipe recommendations?
 

Hi,

Bought a Blue BRZ and want to work on it.

The car appears to have CBE, CAI. PO says that while under the car, since the stock overpipe and frontpipe (with cat) are a little rusty (and restrictive), I may want to get new ones at the same time. I get the restrictive thing - when we removed his silencers, the whole car felt more powerful and responsive!

Other than during an ownership change, there is no inspection or smog, so I was originally thinking of getting a catless frontpipe.

I also like noise / sound, but I do not want to attract attention from cops or get complaints from neighbors, so I am thinking get something that does not make things louder than they already are.

I also learned what drone is recently. I test-drove a BRZ with an Injen exhaust (no drone), a GReddy (very drony), and this Nvidia I am told can be slightly drony at certain speeds.

After researching this the last few days and watching nonstop Youtube videos, it looks like the HKS Dual Resonated Front Pipe keeps noise reasonable and retains and/or augments the subie rumble nicely (and I really like the subie rumble - it sounds very similar to my former 911). The HKS is also reasonably priced. However, it doesn't have a cat.

It would be nice to have a high-flow cat (HFC) because if a cop happened to look under the car I think they can see the cat. (The headers cannot be seen with the panel covering them I am told). Also, if we ever do get smog tests back, or I move to US state with smog tests, I am told an HFC alone even with the Tomei headers could probably get me through an emissions test.

On the other hand, if a cop or someone is looking under a car, it seems those resonators look like HFCs, so would they be able to tell the difference? Or if I give the car to my son later on, and I don't want to swap out parts again, could a mechanic quickly spot the difference between a cat and resonator?

So I guess my question is: does HKS make a resonated HFK also? I was looking at the Nvidia HKS front pipe and it is quite expensive and I'm worried that it is also loud. Other decent choices appear to be from Perrin, JDL, and Berk -but I think the Berk is loud, even with a cat, no?

On the overpipe, I was trying to find a good quality one at a reasonable price. Nvidia, Tomai, Motiv seem a little expensive, but the Gruppe-S one seems pretty reasonable and high quality as well.

Last but not least, do I want to get a combined frontpipe / overpipe? I read about Nameless makes one - are they a good quality? In Canada I also found this other combo for about $550 US, but, but no idea on loudness/quality:
FT86MS Front Over-Pipe Combo (w/ 3" diam, 1 Resonator, 1 non-EPA CAT)

The stock front pipe is the best at controling DB and rasp. With an off the shelf tune there likely won't be much of a difference in terms of power going to a HFC FP.

Gruppe-s OP is identical to the Tomei. I run the gruppe-s header + OP and I am satisfied with quality and fitment.

Ft86MS are local to me. Their FP/OP combo is relatively new but I've heard good things about it.

RToyo86 - cool, the PO said the overpipe and stock frontpipe are rusty and replacing those would make the whole exhast system nice and shiny new / less restrictive from stem to stern.

Good to know the Gruppe-S is solid - in the pics at FT86 it looks like it is very smooth. I also just came across a Megan Racing overpipe from XIII Motorsports in Brampton, price looks even slightly better.

I like the HKS dual resonated but would prefer to have a cat i there, so looking around for the JDL Ultra Quite Front Pipe - seems hard to find. Ok thanks, take care!

Update: Have been emailing with JDL Auto. They can build me an Ultra Quiet Front Pipe + Overpipe combo, for a reasonable price. After more research on the overpipe's I found out that the Gruppe-S and Tomei overpipe's are not a full 2.5" , but the JDL's overpipe is.

I guess JDL Auto can make their unit in 2.5" or 3", but they recommend ordering one that is 2.5" at both ends, because that works better with a NA engine, and because it will bolt up nicely to the Tomei header and the Nvidia N1 CBE.


JDL Auto can also make it have a flat 2 bolt flange or a donut. They recommend donut because they say that's what the Nvidia N1 uses. This is kind of greek to me (I am a computer guy who likes cars but hasn't worked on them himself too much) ....but isn't a donut style flange not as good? If so, why would Nvidia use one?

Also, is a flange the same as a hanger? I think I found in another thread on this board that some people use a hanger from the WRX STI which holds the BRZ/FRS exhaust more securely with less vibrations?

Ok I think I can answer my own question, after reading many helpful threads here. OK so despite the name, apparently donut gaskets are good because they can provide some flex in the system, preventing welds being stressed and braking. Seems like the 1 donut gasket in the FRS/BRZ exhaust system is between the frontpipe and midpipe, and you want to tighten the bolts having springs to squeeze the donut in there. And, per thread 141802 on this board, it is best to ditch the donut gasket that comes with the JDL UQFP, and just buy and use a Vibrant gasket 10108G. I made a little diagram, but I can't seem to upload it (need to put it somewhere and paste the URL here).

My ultra quiet JDL was not so quiet with a catless header. Went back to stock FP.

Thank you that is very helpful information. In part the purpose of buying a front & mid-pipe was to make the entire exhaust new/shiny (the front and overpipe are rusty) - but it was also because if I was going to learn to do this myself, might as well do that while I am under the car.

So now my main reason to get a front and mid-pipe would just be to make it new, and.. to eliminate the restriction, can the car take advantage of a more free-flowing cat and the greater than stock diameter of a 2.5" pipe, and take advantage?

I did not notice any loss of performance going back to the stock FP. I have though about doing an E-tune or a dyno tune but there is very little to gain over the OFT stage 2 tune. Sure someone will comment a protune is better but probably not worth the money for DD. You want more than stage 2 you gotta go E85 or FI.

All the OFT is, is a tool to interface to the car to upload new bin files. Once you have used it to upload a bin, the only other thing it does is datalog. The only way to know is to datalog the car before, then datalog it after and see if it is still happy.

FP is more for sound control and where you'd want to have a high flow cat if you have a catless header so your car doesn't reek. Performance gains are usually negligible. I have an apexi that has high flow cat and large resonator and it keeps my exhaust at almost stock levels with absolutely no rasp.

With local bylaws cracking down on noise pollution and ticketing drivers with modified exhausts, I'm glad i went the path I did. No excessive noise to catch the ears and exhaust tips aren't excessively large to catch the eyes of cops.

@BoxerRumble I found out how to get boxer rumble without having the to change anything in the exhaust. 130,000 miles on my car and I now just discovered this.. It's an actualized, good subaru boxer sound.


I just installed the "positive traction kit" and "positive shift kit" (whiteline and perrin upgrades) on my car and it tightens up the mounts including ones that attach or resonate with the exhaust. Result? The car's chassis acts like a speaker and you'll hear a natural rumble when you are riding beside other cars, passing under bridges, etc. Now the car is quiet when you need it, loud when you want it, and it has a lot of extra pep in the drivetrain to match the sound.