Changed to 2" J's Racing Cat Delete and 2" J's Racing B-Pipe
Previous Setup --> 2" Flo Pro Max Muffler

I'm probably gonna catch some flack for this (Maybe a lot) but here it goes. Want to share an idea I have since I keep reading over and Over and OVER again that high revving Hondas make the most power with a 3" exhaust.

No...I am not going with 3". However, I do plan on going with 2.5"....sorta. I want to apply the same concept that I found works on the intake side with the exhaust side. I want to reduce the exhaust diameter by .25 every time it hits a 90 degree turn. This is to keep exhaust velocity high but avoid being restrictive from being to small. So this is what I want to do -->


I start with 2.5" 2nd cat (or just after it). Once it hits the 1st 90 degree turn, 2.25" piping. Hit 2nd 90 degree turn, 2" piping. Then through 2" resonator, then through muffler. I want to come to a compromise between top and and low end.

Any thoughts/feedback?

**Update** I'm already done with Stage 1 of this project. I couldn't get it out of my head so. Here is what I ended up with for the moment. I started with the 2nd cat, then opened the exhaust up to 2.5". It's 2.5" through both 90 degree bends then it goes to a 2.25" Resonator and a 2.25" Hi Pro Flow muffler.



And some pics of the setup. It's all 'crushed bend'. I know, I know....mandrel bends are the best. There are no mandrel benders out here and no aftermarket exhausts for this Fit yet so. Lets get her done!




The muffler used is a 2.25" Hi Pro Flow Max muffler. I had a 2" High Pro Flow Max on that I posted pics of. The car sounded now different than stock and it was a straight through muffler so I stuck with what worked. It's not pretty I know. Wasn't meant to be. When things get ugly, it's gonna look the part. This ain't a show car.



The resonator I purchased was solely to keep exhaust gas velocity up but keep noise down. So I purchased a 2.25" Vibrant Ultra Quiet Resonator. It was $91.50 from Verocious Motorsports. I drove down the street to pick it up to be installed.

Link to Resonator --> Vibrant Ultra Quiet Resonator


I can't feel any loss of torque anywhere and it feels like the car can BREATHE. I'm doubting all my feelings on it and opinions. I need to record some runs and take it to the track to gather data. It's no longer quiet but a slight hum way in the background. Very low, deep! My wife didn't really notice it at all. No raspiness but the video I took of it makes it sound louder than what I thought it was. Doesn't sound like that from inside car. Will post up in a bit. It feels REALLY good though. Like it's faster but I call B.S. until I get real data.

This stage one. I have some testing to do than the 2nd cat may be replaced with a 2.5" unit or removed altogether.....NEXT WEEK. Stay tuned!


Gawd...the muffler sounds LOUD on here to me. Hahaha! I wonder who will win between it and the PRM intake you can hear in my other videos.


**Update 12-11-14**

Added a J'S RACING GK5 FIT3 SUS Circuit Converter AKA J's Racing Cat Delete. It bolted right up without any issues and came with a 'cap' to cap off the EGR.
The J's Racing cat delete pipe is 2" in diameter.






The J's Racing cat delete outlet flares up to about 2.25". This is important to know because if you bolt it up to the stock piping, the exhaust gases will come into contact wiyh the stock 'B' pipe inlet at the flange. This can cause some raspiness my mechanic told me. It'll definitely cause some turbulence and interrupt the exhaust flow somewhat. I'm not mechanic or expert but I'd recommend at least having a 2.25" B pipe (Mid-pipe) to connect to the J's racing cat delete. I had the flange widened up to 2.5". Please look at my pic above at the 2nd cat converter flange that mates up to the 'B' pipe. Look at the 'B' pipe's inlet and you'll notice how small it is before it opens up to 2.5". Then look at this.



Eliminating the cat converters brings out a LOT of exhaust noise. I already have a decent sized 2.25" Hi Pro Flo Max Muffler and 2.25" Ultra quiet Vibrant resonator and they both could not contain the beast. Loud is subjective and different with different people. My definition of loud exhaust is if you drive around for a while (Hours, Days, Weeks) and you still notice your exhaust, all the time, it's too loud. The whole 24hrs after J's racing cat pipe, I noticed the exhaust noise every moment of driving. I should've forgotten about it an hour or two after driving to think about other things and THEN notice the exhaust when my mind went back to it. Anyways.....I decided I needed another resonator added. So I picked up another Vibrant resonator BUT the exhaust shop suggested I go with a longer, slightly bigger muffler instead. So I compared the two.
Both are 2.25" in/out center. The top and left is a Xlerator muffler (Part# XS0425). The bottom and right is another 2.25" Vibrant Resonator. I chose to go with the muffler. It felt a little bit heavier so I was hesitant to get it but I reminded myself that I wanted to get rid of the high exhaust note. Both the resonator and muffler are straight through designs.




And before anyone says anything about adding restriction to the exhaust, just like Vibrant resonator that is already installed, the Xlerator muffler is a straight through design. It's not restrictive.



A close up look with the Ultra quiet Vibrant Resonator going into the Xlerator muffler.



A further out look of the whole exhaust, including the Hi Pro Flow Muffler.




Here is the whole exhaust breakdown!
1) 2" J's Racing Cat Delete Pipe,
2) 2.5" B-Pipe (Midpipe),
3) 2.25" Vibrant Ultra Quiet Resonator,
4) 2.25" Xlerator Muffler,
5) 2.25" Hi Pro Flow Max Muffler

Short video revving it a little in the shop. Exhaust is now 2" J's Racing Cat Delete Piping, 2.5" piping to 2.25" piping, 2.25" Vibrant Ultra Quiet Resonator, 2.25" Xlerator muffler, 2.25" Hi Flow Pro Max Muffler.

I am totally and utterly happy. This is EXACTLY how I wanted my exhaust. I have no idea on how it performs. If I can test it at a track, I will as soon as I can (This weekend is last weekend track opens). I will be testing on my Android Torque software but I don't report those number. I'll know it works though by testing the 0-60, 1/4 mile time and hp/tq info as the software has been very consistent. So, I'm done with the exhaust. I still have a check engine code --> Check engine code read --> P0135 - Powertrain, O2 Sensor Heater Circuit (Bank 1, Sensor 1). I will work on that in due time.

 

Do the same thing but start with 3", get rid of both cats and probably add a bigger resonator so you don't get the drone. Good luck!

 

What makes you say go with 3"? You must've been reading the same stuff I have. Just curious!

 

Well it really doesn't matter what diameter you start with because the smallest diameter will contribute to how much exhaust will get out. Insuspect using a 3" will give more surface area for heat to dissipate earlier. This is just a guess not a proven fact.

Another thing, the cats are what taking away the power and causing more obstruction in the flow of travel. The bends themselves should be fine. If I were to make an exhaust, i would put a downturn right at the first bend to maximize power.

 

You are reading exhaust velocity effect backwards. You actually want it to stay the same or get slightly bigger, since the cooler exhaust is, the slower it moves. Having the piping get larger tends to allow the exhaust to still escape at good speed.

However, starting with 2.5 and ending with 2" is not bad. I have full 2" catback combined with my WeaponR that has 2 1/8" and it did have a positive effect at the track. Didnt really notice the performance difference too much. Getting rid of the cats and teh stock muffler helped the most. Heck, the stock muffler had a BURN spot in the center, where it was restricting flow so much it was super-heating the muffler.

 

You're right keeping it bigger then go smaller creates back pressure. I'm coming from a turbo car where biggest to open wastegate is best

 

are you testing these setups on a dyno to see if there is improvements being made?

I don't think there will be much of a difference since most of the pulse tuning/sacavaging potential is eliminated with the integrated manifold.

 

I will no longer be doing dynos. It was starting to cause problems in my marriage because I tested EVERYTHING, all the time. I needed to know if I made or lost power. You could probably Google 'Myxalplyx Dyno' to see some of the things I've dyno'd. It became an obsession! My Torque Pro software is all I need now and it's free.

I do have some additional data points that ya'll may find interesting. I'm comparing my previous stock exhaust setup with the 2" Max Pro Flow muffler to my current setup with the 2.5"-2.25" resonator and Max Flow Pro muffler. I'm comparing my 3 runs from Thursday night and 4 runs from last night. Here's what came up.

The numbers below are the Max Grams Per Second (g/s), Max Horsepower (hp) and Max Torque (tq)

Thursday Night
1st run 99.7g/s, 116.5hp, 98.7tq
2nd run 99.7g/s, 117.7hp - 100.1tq
3rd run 100.5g/s, 114.6hp - 99.9tq
Average:
99.97g/s, 116.27hp - 99.57tq

Friday Night
1st run 102.4g/s, 123.5hp/104.2tq
2nd run 102.3g/s, 117.3hp/106.1tq
3rd run 102.3g/s, 123.1hp/109.9tq
4th run 102.0g/s, 119.3hp/101.1tq
Average:
102.25g/s, 120.8hp - 105.33tq

Potential gains --> 4.53hp - 5.76tq


I'll take what I can get. I'm happy with what I'm seeing so far. Just note that my trap speeds are average 87mph now with a boost to 88mph if I'm lucky (At Cecil County Dragway). I need to get back to this track and see if I can break into the 89mph territory to confirm all this.



***Personal Notes***
Maf sensor Grams Per Second (g/s)
For every 2.28g/s gain is equal too 4.54hp.
In other words every 0.5g/s gained is equal to 1hp.

 

True! Also, the right size exhaust is supposed to help pull gases out of the combustion chamber during the exhaust stroke, by creating a vacuum. To wide they say and this doesn't happen. But I'm not expert in this stuff. That is what 'they' say though.


Kylerwho, that makes sense. This is why I test things though and try to keep an open mind. I remember reading tons of posts here that stated adding an intake and exhaust is pointless and will yield no hp/tq gains without a Flashpro, Hondata or something else. It sounds believable! My past experience with modifying all my cars don't say this though. This is why I test but I understand I'm not better than the next person.

If tiny bits of hp/tq continue to be gained, we'll be slowly approaching 14 second territory without going forced induction or nitrous. Who knows what a manual GK fit can do as well. It's all refreshing and exciting to be learning on this new platform. (And no, I don't think I'll hit a 14 second 1/4 mile time but I didn't think I'd hit 15's either. Not N/A and Auto *CVT*!)

 

the scavenging effect is diminished quite a bit because of the cylinder head collector, but there is still pulses.

Keep in mind, one exhaust valve of each cylinder 2 and cylinder 3 have a direct shot out, yet one valve each of cylinders 1 and 4 have much longer to travel.


Your best bet is to get rid of the cats, go to 2 or 2.25 piping for the downpipe, and heat-wrap the entire pipe until it reaches the catback setup you just added.

the GE and the CRZ share the same oem honda gasket for the head flange. you may want to see if you can find a used weaponR downpipe (just the upper piece) and cut it off at least 3-4 inches past the primary O2 sensor bung, and have a shop weld you up a cat delete. Heck, maybe the CRZ piece or the GE piece will work for you. the GE and CRZ themselves cannot interchange, but I do NOT know which car the GK is based on.

you can find a fairly reasonable priced aftermarket new highflow cat on ebay if you dont wanna bother with CEL eliminators or a check engine light. weld it in and still be legal I guess.

 

sorry but that is some ugly welds and ugly exhaust

 

since when do welds need to look cosmetically good to BE good?


Some of the factory robot welds look shitty, and they last just fine

 

*12-11-14* Exhaust is now COMPLETE

Updated the first post with new parts to the exhaust. New parts include....
1) J's Racing Cat Delete,
2) 'B' Pipe (Midpipe) inlet flange modification,
3) 2.25" Xlerator Muffler added between Vibrant Resonator and Hi Pro Flow Max muffler.

Pics are being included.

 

What are your initial thoughts? stronger midrange? perhaps lower low rpm power with actual high rpm increase?

Curious indeed! <<<

 

My butt dyno has always been off. Way off! So I never really state what I think it is doing. But since you asked, I feel no difference. Feels the same except it is louder.

Also, I re-installed my PRM intake and did three test runs. I did not have my rear seats removed or my spare tire like I usually do. There was no difference in 0-60, 1/4 mile time or hp/torque to the wheels than my previous runs done in the same conditions, same temperature, same road.

That's the bad news!


Something seems really screwy with my data but it is what I got. Maybe it has something with my check engine light being on now along with disabling my traction control, etc.

Here is the good news! THIS I really like!
My last ray of hope was looking at the maf sensor grams per second (or g/s). This was always an indication that the car is sucking in more air, making more horsepower. I always looked at what the g/s peaked at to know if I made more horsepower or not. After each modification, it would creep up.

The last four runs I did on the same road with the same temp showed these for my maf sensor readings. These are the peak g/s that the maf showed.

104.8 g/s
103.7 g/s
104.8 g/s
103.3 g/s

Average: 104.15 g/s

It was always a major victory just getting the number to go up by one. But this is what the g/s numbers showed tonight after the J's racing cat delete pipe addition.

111.2 g/s
111.2 g/s
110.3 g/s

Average 110.9 g/s

That is major to me. Take it with a grain of salt. I tried to convert this to horsepower. I read the formula is (maf g/s) / 0.82 = Horsepower

104.15 g/s = 127hp (Wheels I'm guessing)

110.9 g/s = 135hp

So I'll say it give approximately 8hp if you want a number. Who cares though right? Need to test this out at the track. I'm hoping Atco Raceway is open tomorrow. Until then (or Spring), this is all for now.

 

Get it tested! In all my years of experience with attempting to get power out of a Honda without tuning support, nothing helps it along then driving it.

Nothing is a better test then the drags or a good circuit track that requires lots of gear changes and variable speeds and inputs.

Flinging my car around the backroads is what really made my custom intake shine. Day to day driving, even around city, didnt really let it show through.

 

Tuning support is here! I posted a thread about it (KTuner ECU Reflash). I'm just waiting for the unit to come in and the tuning begans. Very exciting indeed!

 

After doing lots and Lots and LOTS of thinking on this, reading and more reading AND going over timeslips in November, December and March, I've concluded that 2.5" is too big. My 'B' pipe is currently 2.5". I'm going to reduce down to 2.25" and I'll keep the rest of my exhaust 2.25" all the way out. If it was a straight run out the back of the car, then I'd keep it 2". I have my own little theory about opening up the exhaust slightly as it hits a 90 degree bend to help flow. Will see how this goes. Need to change this up this upcoming Friday.

I was fully expecting to hit a 15.0-15.1 this past Friday but I my time was actually worse than previous testing. I had to keep looking at time slip data and was trying to remember what I did different during specific runs.

Stock cats 1.75" to 2.5" 'B' pipe, 2.25" resonator and 2.25" muffler
15.2 - 15.3 @ 90-91mph
**Runs done 11-14-14**

J's Racing 2" Cat delete pipe, 2.5" 'B' pipe and 2.25" resonator and two 2.25" mufflers (Straight through design)
15.5 @ 88mph
**Runs done on 3-13-15**

I lost 2/10ths and 2-3mph in the 1/4 mile. I did do a Ktuner reflash to test 'something' but I do not think that is affecting things in a negative manner. Once I go back to a 2.25" crush bent 'B' pipe, will retest and hope for the best. Excited about this actually. It's all a good learning. I only used runs done on the same track since at different tracks I get different times in like conditions (Englishotwn, Atco and Cecil County).

 

I got a very nice gain when I went from decats+oem midpipe+straight-through axleback to decat+2" catback that was loaded with a thrush 2" offset muffler and 2" thrush glasspack.


2" is definitely the sweetspot on these motors if they stick with the stock camshaft and intake manifold.


2.5" would be great if you get a proper plenum style intake manifold (aka, runners that are NOT long enough to wrap around the engine bay!!) and even a very mild camshaft upgrade (the future awaits with support?!!)

 

Thanks for the feedback 13Fit! I'm waiting for an update from Deltacams on the camshafts I sent in. I will be giving them a call today. Will start with 2.25" 'B' pipe to work with the cams and go from there. If Deltacams aren't successful, then I'll work with the 2.25" and 'B' pipe with the stock cams and see how it goes.