So I have my Injen long tube/cold air induction, love the sound, love the minor performance gains however now I am ready to invest some money (not to the likes of TT) to start seeing some tangible gains. So I know now the next big bottle neck is the exhaust. From the research I have done on this site for the past couple of years is that the biggest bottle neck in airflow are the Cats. I found many people here like the resonated HFCs by Fast Intentions.

My Questions:

Is getting the full FI exhaust system really any different from "simply" replacing the cats with FI HFCs?

Is there a noticeable power difference?

I am under the impression that the stock exhaust on the G37 is not too restricting when the cats are replaced with HFCs and therefore no real gains are realized with full exhaust systems.

I plan on installing FI HFCs and then getting an UpRev ecu tune... no TT Skyline, but I think it is enough to make me feel better

 

Some of the power differences are posted on the Fast Intentions group buy thread:

https://www.myg37.com/forums/group-b...-discount.html

If you only have intakes and rhfc I don't think it's worth it to get the uprev; if you get the full exhaust then we're talking I love my Fast Intentions by the way

 

Thanks dude !

So I am assuming that:

You have the whole exhaust system and saw gains?

 

Yup I have the resonated high flow cats and resonated exhaust and I have the uprev tune which on its own gave me 25whp. I can definately hear/feel the difference One of my buddies had a G37S with custom exhaust and we did a couple of runs and I beat him everytime

 

Biggest restriction is in the stock cats and OEM Y pipe , I made 305whp with takeda cold air , kinetix hfc and megan y pipe tuned with uprev My car feels great and still has that OEM sound (just a little more aggressive under load) I had a full exhaust and test peps before annoying to say the least

 

If you look at the link provided that shows FI results, the HFC only added 4 hp to the cat back. I had FI resonated HFC on my 350Z HR for 1 1/2 yrs with Gemini Cat back and went back to stock cats recently for Ca smog. It drives BETTER (more low end torque and smother shifting) with the stock cats back in! Noticeably better. It also idles smoother. I would STRONGLY recommend using a cat back of your choice a leaving the stock cats in! Modern cats are NOT that restrictive and are designed to flow very well with the *honeycomb* design. The amount of increased flow with the HFC is negligible and you will get more negative effects than any possible TOP END gains in HP. Also, most sound enhancement is attained with the catback, not the HFC, which will just make it LOUDER. Just my 2 cents gleaned from my own experience. No BS here.

 

I am going FI Resonated X Pipe Cat Back and FI Resonated HFCs. This will be paired with my Injen Long Tube CAI and finally topped with an UpRev tune somewhere here in NJ.

 

Wow that sounds expensive ($2500+) and loud. I hope you post install pics and sound clips.

 

I saw gains from just putting in HFCs and an axleback.... From what I have read around here the mid pipes don't really add muck in the HP department. The biggest bottle necks for the exhaust system are the cats and mufflers. A lot of noise comes from the cold air intakes as well. All those nice parts really don't do anything but make noise until you get the engine tuned. That part is by far the best of performance modding.

 

warped - you got any vids of your Tanabe's & Kinetix combo? How's it sound inside the cabin in terms of drone with the automatic?

 

https://www.myg37.com/forums/g37-sed...nd-review.html

Here is my review and how I installed the HFCs on my G. There is also a YouTube video of the car after the installation. As for drone, there is a slight drone while out on the highway but it's not over bearing and is easily drowned out by the stereo.

I have a few videos if you visit my profile page and look under statistics and threads started by me. I have three videos in all.

 

I'm in the same boat as you OP, except already have the FI RHFC installed and a Gen 3 installed. I found the Gen 3 took away from the VQ sound, but the RHFC"s brought it right back. I will be purchasing a CBE next tax return. I'm either going with FI, Motordyne or Ark, but leaning towards FI since I already have the RHFC's.

I think you could get away with just the cats, but, would sound and perform better with the whole system, I'm even thinking about adding headers.

 

I live in Cali so cats are out of the question. I plan to do CBE and Y-pipe and possibly intake. After that tune since that is all the "go mods" I can feasibly do and still be legal. After the tune what gains do you think I would see? (37S 6MT btw)

 

The Y pipe is also very restrictive , It has a 1.7" inlet after the cats

 

If you are going to run a CBE system the Y pipe is included .>>Catalytic Back Exhaust<<