Rochester's new G
03-17-2014, 08:25 PM
#332
I had FI Resonated Cats installed this morning. No pics of the installation, no videos, but there is a picture of them on my living room floor a few pages back, if you want to see them.
They were installed against the OEM shorty headers, and the OEM catback. So this work was just for the cats. Nothing else. The reason I went with FI was for quality reputation and their J-Bung design to spoof the O2 Sensors. But also because FI is the only one making a resonated cat, and I've come to the interwebz opinion that if you want to avoid rasp in an aftermarket exhaust consisting of HFC and Catback, then the FI Resonated High-flow Cats are the way to go. In other words, I'm future proofing my exhaust upgrade down the line, for whatever exhaust I decide to go with. (And at this point, it's looking like ARK.)
Installation
The install was a b1tch. Although more so for my mechanic, because I didn't do the work. For whatever reason, one bolt on each cat got stripped, between the cats and the headers. In the end, they had to cut off the corner on the cat flange with the torch. Total PITA, but there was no collateral damage, and no damage to the header flange. Once the OEM cats were finally off, the new ones went right on easy.
Vibration
At idle, there's a noticeable vibration under my seat that wasn't there before. I suspect it has to do with that cross-piece that the OEM cats were connected to, and is no longer applicable to the new ones. It's not an unpleasant vibration, and it goes away outside of idle, but still... he might fabricate and weld the cross-piece to fit at some future point. At this time, don't care. Other than that, no changes, no issues.
Sound
At idle, the car is just a little bit louder, but that really depends on the surrounding location... on the road, in a parking lot, in my garage. There's a difference at idle, but it's barely perceptible. When driving normally, the exhaust tone seems completely unchanged. When driving hard, the exhaust is noticeably louder, particularly at WOT. But it's hard to distinguish between exhaust sound and intake noise, because intake. All in all, unless you were to drive my car before/after, you'd be hard pressed to notice the mod.
Some would say that's perfect, but honestly, I'm a bit disappointed. I like noise, and this isn't it.
Gains
Alfredo's got the build thread where he dyno'd after every mod, and he saw significant un-tuned gains after adding the RHFC. My butt-dyno totally agrees with that, because there is a lot more grunt going on here. When you pull hard in 1st and 2nd gear, it pulls more and it does it longer. And when you go WOT on the highway, ripping 3rd gear to red-line... well, there's just more there than there was before.
Years of hanging out on this forum had led me to the conclusion that cats are the most significant bottleneck on these cars. Now that I've replaced mine, while retaining the stock cat-back, I completely stand by that opinion.
Final Assessment
So I'm happy about the added grunt, because it was more than I expected. But I'm very disappointed in the lack of exhaust noise, because it's much less than I expected. Right now I'm trying to reconcile reality with my expectations, and writing this stuff down helps with that.
The big mod for 2015 was supposed to be 4.083 gears, but now I'm thinking cat-back, just because I really want to hear my exhaust.
/review
They were installed against the OEM shorty headers, and the OEM catback. So this work was just for the cats. Nothing else. The reason I went with FI was for quality reputation and their J-Bung design to spoof the O2 Sensors. But also because FI is the only one making a resonated cat, and I've come to the interwebz opinion that if you want to avoid rasp in an aftermarket exhaust consisting of HFC and Catback, then the FI Resonated High-flow Cats are the way to go. In other words, I'm future proofing my exhaust upgrade down the line, for whatever exhaust I decide to go with. (And at this point, it's looking like ARK.)
Installation
The install was a b1tch. Although more so for my mechanic, because I didn't do the work. For whatever reason, one bolt on each cat got stripped, between the cats and the headers. In the end, they had to cut off the corner on the cat flange with the torch. Total PITA, but there was no collateral damage, and no damage to the header flange. Once the OEM cats were finally off, the new ones went right on easy.
Vibration
At idle, there's a noticeable vibration under my seat that wasn't there before. I suspect it has to do with that cross-piece that the OEM cats were connected to, and is no longer applicable to the new ones. It's not an unpleasant vibration, and it goes away outside of idle, but still... he might fabricate and weld the cross-piece to fit at some future point. At this time, don't care. Other than that, no changes, no issues.
Sound
At idle, the car is just a little bit louder, but that really depends on the surrounding location... on the road, in a parking lot, in my garage. There's a difference at idle, but it's barely perceptible. When driving normally, the exhaust tone seems completely unchanged. When driving hard, the exhaust is noticeably louder, particularly at WOT. But it's hard to distinguish between exhaust sound and intake noise, because intake. All in all, unless you were to drive my car before/after, you'd be hard pressed to notice the mod.
Some would say that's perfect, but honestly, I'm a bit disappointed. I like noise, and this isn't it.
Gains
Alfredo's got the build thread where he dyno'd after every mod, and he saw significant un-tuned gains after adding the RHFC. My butt-dyno totally agrees with that, because there is a lot more grunt going on here. When you pull hard in 1st and 2nd gear, it pulls more and it does it longer. And when you go WOT on the highway, ripping 3rd gear to red-line... well, there's just more there than there was before.
Years of hanging out on this forum had led me to the conclusion that cats are the most significant bottleneck on these cars. Now that I've replaced mine, while retaining the stock cat-back, I completely stand by that opinion.
Final Assessment
- Pretty expensive mod, adding together the cost of the cats and a shop-installation. Particularly when there are problems (like stripped bolts.)
- A little more vibration at idle, that we can probably correct.
- Virtually no-change at all in tone and volume, except at WOT.
- A small but noticeable amount of improved throttle response, likely from an increase in torque. And a very nice increase in how much and how long the car pulls at WOT.
So I'm happy about the added grunt, because it was more than I expected. But I'm very disappointed in the lack of exhaust noise, because it's much less than I expected. Right now I'm trying to reconcile reality with my expectations, and writing this stuff down helps with that.
The big mod for 2015 was supposed to be 4.083 gears, but now I'm thinking cat-back, just because I really want to hear my exhaust.
/review
It seems strange the overall volume wouldn't increase when the largest restriction has been removed.
03-17-2014, 09:26 PM
#333
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I feel with your skepticism. Surprised me too. Maybe there's more nuance to appreciate after a while... It's just Day One, after all. But I suspect itis what it is.
03-17-2014, 09:42 PM
#334
Maybe it is the fact that they are resonated
. I would still be interested if you are willing to put a take off shot or two even without the stock comparison just to judge the overall sound and quality.
. I would still be interested if you are willing to put a take off shot or two even without the stock comparison just to judge the overall sound and quality.
03-17-2014, 09:46 PM
#335
Nice review John, that install seems pretty typical, that one of those projects that seems to snag everyone that tries it in one way or another. One reason why I'm not in a big hurry to do this one.
So dead on about the OEM exhaust, it's one big fraud~the back tips look like they might mean business but it's just one big restriction
BTW how many hours was the install? (if you posted it I missed it )
So dead on about the OEM exhaust, it's one big fraud~the back tips look like they might mean business but it's just one big restriction
BTW how many hours was the install? (if you posted it I missed it )
03-17-2014, 10:19 PM
#336
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They started the work thinking it could all be done from underneath, but eventually I had to remove the intakes for access from up top. Which meant removing the engine cover for access to the rear couplings, which means removing the FSTB. Dominoes... LOL
With the problem of the stripped bolts, the job took a little over two hours, two mechanics, a lift, an acetylene torch, a box of donuts, two pots of coffee...
With the problem of the stripped bolts, the job took a little over two hours, two mechanics, a lift, an acetylene torch, a box of donuts, two pots of coffee...
03-18-2014, 08:05 AM
#337
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Nice about he RHFC, I loved mine .I will get them again and you did pick up power it the midrange I pick up a lot in there unturned on mine also, I made more than when I was tuned with the stock cats. How does it sound with the stock system?
03-18-2014, 08:31 AM
#338
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It sounds pretty much like it did before.
Based on my experience with this, I'm saying Resonated HFC's from Fast Intentions, as installed on the stock cat-back, are a noticeable power mod, but without added noise of any appreciable measure. For some people, that's a very good thing. For others, it's disappointing.
Of course, I also have intake noise compromising that assessment, so take it for what it's worth... just another forum opinion.
Based on my experience with this, I'm saying Resonated HFC's from Fast Intentions, as installed on the stock cat-back, are a noticeable power mod, but without added noise of any appreciable measure. For some people, that's a very good thing. For others, it's disappointing.
Of course, I also have intake noise compromising that assessment, so take it for what it's worth... just another forum opinion.
03-18-2014, 09:06 AM
#339
The OEM catback is probably over-designed. It's been a while, but I remember having to work the throttle pretty hard to get the kind of thrum I was looking for. More air doesn't necessarily mean you get more sound. Whatever engine sound you produce is going to have to go through the OEM catback resonators regardless, you've just added one more resonator to the mix.
03-18-2014, 12:56 PM
#340
A quarter past stripped
Nice write up Rochester. The sound will increase a bit and get more throatier as the cats break in. I'd suggest Tanabe exhaust for you. They have plenty of growl even @ idle, then @ WOT you WILL hear the exhaust over the intake.
I believe you will start to notice a funny idle as well. While sitting at a light you'll probably see your revs jump around a bit. My tune completely fixed that problem for me. I had an odd vibration as well after installing the cats. That disappeared with the tune too. Hope you figure out what's best for your liking, and you get those rims on soon!
I believe you will start to notice a funny idle as well. While sitting at a light you'll probably see your revs jump around a bit. My tune completely fixed that problem for me. I had an odd vibration as well after installing the cats. That disappeared with the tune too. Hope you figure out what's best for your liking, and you get those rims on soon!
03-18-2014, 12:57 PM
#341
Very extensive review John! Glad to see you were still happy about your purchase and installation, even after discussing what your outcome was and what you were expecting.
I'd like more information if you end up having some sort of support bracket fabricated for the HFCs. I talked to my tech about this also and he mentioned making something for this. If you beat me to it, I'd like to hear about the design and results.
I'd like more information if you end up having some sort of support bracket fabricated for the HFCs. I talked to my tech about this also and he mentioned making something for this. If you beat me to it, I'd like to hear about the design and results.
03-18-2014, 01:55 PM
#342
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Let's compare at the meet-up next month.
Last edited by Rochester; 03-18-2014 at 02:04 PM.
03-18-2014, 03:42 PM
#343
If I pursue this later this spring/summer, I'll be sure to bump this thread with information. After driving around today (Day 2), I started thinking how that vibration at idle will quickly become the new normal, and I may either forget or ignore the idea of fixing it. IDK, really. Need more time to see what happens and how much it matters to me in a few months. As of yesterday morning, it really mattered. But just one day later, not so much. Funny how that happens.
Let's compare at the meet-up next month.
Let's compare at the meet-up next month.
03-18-2014, 04:31 PM
#344
A quarter past stripped
If I pursue this later this spring/summer, I'll be sure to bump this thread with information. After driving around today (Day 2), I started thinking how that vibration at idle will quickly become the new normal, and I may either forget or ignore the idea of fixing it. IDK, really. Need more time to see what happens and how much it matters to me in a few months. As of yesterday morning, it really mattered. But just one day later, not so much. Funny how that happens.
Let's compare at the meet-up next month.
Let's compare at the meet-up next month.
It made the left fog light lense start to rattle and it could be heard in the car while stopped. A bit of cardboard shimming stopped the rattle but the tune solved the problem completely.
03-18-2014, 04:46 PM
#345
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Why? Did you increase your idle speed with the tune? Because I found just a tick over stock idle RPM and the vibration goes away.
Hmm... I'm thinking the AT in gear but at a dead stop is a different experience than my 6MT at a dead stop with the clutch in. So apples to apples, you're talking about when the car is in PARK or NEUTRAL, right?
Hmm... I'm thinking the AT in gear but at a dead stop is a different experience than my 6MT at a dead stop with the clutch in. So apples to apples, you're talking about when the car is in PARK or NEUTRAL, right?