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Which Cat Back Exhaust is the best for the Is-f

39926 Views 41 Replies 18 Participants Last post by  BriggsRT
hey guys, i just recently bought the Is-f and i need help deciding on which Cat Back Exhaust system to go with...
i keep looking up diff types on youtube but im still so indecisive...
i looked up:
Royal Exhaust
Borla Axle-Back Exhaust

if anyone out there owns these exhaust systems and can give me some feed back to which one i should go with that would be greatly appreciated!!
as well as i was wondering if they all add the same more or less hp to the car or are some of the systems give out more hp then others?
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I would say Joe-z, borla, or just go to a reputable custom muffler shop and have them do 2 1/2" piping after the cats with muffler deletes.
im sure someone will come in and bash but so far the most hp from one has come from the ISSForged exhaust.
im not here to bash. but the ISS exhaust is the ugliest exhaust i have ever seen. it just looks way too out of place on the back of the ISF.

IMO JoeZ is the way to go. its lighter then stock. it makes alot more power. and it sounds perfect. it also fits like a glove.

as far as those ISS dyno numbers. until you can put a joez on the same car, and run a dyno with it, and then run a dyno with the ISS on, and compare, with equal temperatures and cool down times. im going to say that dual 2.5" catback is as much power as its going to make, and they are both equal. 2, 3, 4, even 5hp....your not going to notice.
I personally enjoy the JoeZ
how much more hp does the ISS Forged exhaust give compared to the JoeZ?
The crazy thing is like every other JoeZ exhaust owner does dyno testing on their car after installing each individual upgrade and posts on this forum or CL. This fact, the quality and thought put into the system, and the fact that VIP is in my area and I have come to find out that their customer service is unrivaled convinced me that the JoeZ was the exhaust that I wanted. The system is a serious, high dollar exhaust. You don't even see quality like this from Dinan, it really is top notch. No expense was spared, there is not one thing hokey or cheesy on the whole system. And for $1600, the price point is quite reasonable for what you are getting. The fit and finish is amazing. And the sound... these cars really should have come with this system from the factory. The car now sounds like it should always have sounded. Not annoying, almost subtle while driving in a civilized manner, but when the throttle is pinned to the floor and the big V8 begins inhaling massive quantities of oxygen, all hell breaks loose. +1 for JoeZ, and a big +1 for VIP. Oh, and while you're at it, pick up the JoeZ intake pipe for $140, money well spent.
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i read some issues with other exhausts such as the borla that it sometimes doesnt fit right when u receive it... and there is a rattling sound when its really hot..? does that ever happened to anyone with the JoeZ? and if ur driving around the city under 2x rpm can u still hear the exhaust..? cuz i remember in my previous rice rocket when i put an exhaust on there it was always so loud driving around to the point where i got annoyed of it and got rid of it

how come joeZ intake is so cheap compared to the K&N intake?
is there a big difference in quality and is it true K&N adds 28hp?
The K&N does not add 28hp.

The Borla exhaust will not rattle when hot unless it's touching something. I think you read my complaint, and basically the problem was that the IS-F does not have much clearance for pipes, so the Borla is a very tight squeeze. This was resolved with a few trips back to the installers. They eventually had to spot weld it in place.

I like the Borla catback exhaust. I removed the K&N intake because it did nothing and just made it ridiculously loud when the car was open throttle. The K&N sounded better when I first installed it, then as the computer got used to it, the growling it made over 3k rpm started to fade away, and the only sound left was a RIDICULOUS growl at 4k+ rpm.
IMO Joe Z intake and exhaust is great so far. Not annoying while cruising.
the reason for the difference in price is that the JOE Z intake is an intake tube that leaves the filter box present. The K&N gets rid of the filter box and makes it a single stage intake. I have the JOE Z and am enjoying it but haven't witnessed the K&N yet. Next plan is the intake and I supposed that I'm going with the Joe Z exhaust to complement the intake
JoeZ is noticeable, but easy on the ears during daily driving. It makes the sound you would expect to come from a sophisticated muscle car. When you get on it, it sounds excellent, but again not annoying or overly loud. The JoeZ intake pipe is just a pipe that replaces the factory resonator pipe between the air box and throttle body. It works, and has been tested and proven time and time again. The JoeZ line of parts are well thought out, throughly tested, superbly executed with better than factory fit & finish, and are proven to deliver repeatable results.
I have the Borla axle back. Fit and finish are good, I had mine unpolished and the mufflers powder coated. Engine "breathes" better, sounds louder and nicer by about 20% except that it has a drone while cruising at 1900-2000 rpm.
I wish there could be a side by side comparo between a Borla equipped car and Joe Z'd car, to see and hear which is better.
I wish there could be a side by side comparo between a Borla equipped car and Joe Z'd car, to see and hear which is better.
I really find that sentence funny. See and hear:confused: In my mind, an exhaust is all about power. More and how much and etc. Sound should be secondary, except that you do want it to be to noisy or have a drone. IOW, sound and power is a tradeoff, with power coming in first.

I know that but I seem to recall that many ask in other threads which of the after market exhausts sound better. Then again "sounds better" is subjective. Oh well...
Here's a comparo done side by side while standing still.
ISS QES Street system and if you want to make some noise with Crazy power The Track System

How much more power does the ISS track system make compared to the JoeZ?
How much more power does the ISS track system make compared to the JoeZ?
I would say the gains are the same....

Here are my Independent Dyno Results.. 22-39 RWHP... ;)

Joe Z (posted Oct 5th said:
PTS / Joe Z IS-F True Dual Exhaust RWHP Gains

~ Released & Debuted @ SEMA 2008 Las Vegas ~

- As a disclosure to ALL, our Best Pump / Fuel choice is only 91 Octane for our IS-F, here in Southern California.

Below is the Dynojet graph of ALL the 6th Gear Runs with the New Exhaust System installed...

This independently tested system, included Two properly tuned resonators & mufflers for optimal performace gains while retaining the ultimate Lexus experience.

Base / Stock Dyno test was 333 Rwhp & 336 Rtq

Run 11 (361.8 Rwhp / 356.4 Tq) = 1st run after initial setup and safety test spin on the dyno
29 Rwhp Gain over stock

* Run 12 (354.8 Rwhp / 353.8 Tq) = 2nd run, which is right after the 1st run.
This run best represents normal operating temps.
This is the run we used to compare with the base numbers.
* 22 Rwhp Gain over stock

Run 15 (371.8 Rwhp / 357.2 Tq) = 5th run which was the last run.
This was just after the two 5th gear runs and a 5 minute shut down / cool down of the engine...
Best numbers of the day due to cooling period.
39 Rwhp Gain over stock

- Joe Z
Best Regards,

Joe Z :)
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