combfilter

iTrader: (3)

I will def. say it's probably the most hp gains you'll get of any exhaust. The sound is wicked if you don't mind that when you drive around normal people in the back will wonder why your lexus is so loud.

YOu might want to review a post i made eon's ago before you purchase though.

https://www.clublexus.com/forums/per...d-exhaust.html

KI_GSE21

iTrader: (5)

Removing the secondary cats will make the overall exhaust setup louder because the exhaust flow is better and the restrictive secondary cats are gone. It's not loud loud, doesn't sound rice or anything like a Civic with a fart can

Kurtz

iTrader: (1)

The secondary cats aren't especially restrictive, gains are in the 1-2 hp range.

It does make it louder though.

MIA_LEX

iTrader: (4)

Yea man I was lokking at your thread very informational. It kind put my mind on a megan exhaust. Now Im on Borla. Tough Decisions here, dont want to make the wrong one.

KI_GSE21

iTrader: (5)

From a performance aspect, tuners perceive cats in general to be restrictive in terms of exhaust flow characteristics. Gains may be minimal, but they add up and work in sync with other performance mods on the vehicle. For people who care about hp/tq, a small power gain makes a difference. Again, it's louder because of greater/smoother exhaust flow.

Kurtz

iTrader: (1)

And in the late 1970s, those tuners were right...because first-gen cats were very restrictive and removing them caused significant, and noticable gains.

That's simply not true of modern cats though.

Likewise, in the 1950s there was a functional reason to have holes in your brake rotors. Now, it's stupid, and does nothing but weaken your rotor and reduce its capacity to hold heat. Technology moves forward.

It's louder because you've removed a part that reduces noise, not for any performance reasons. The tanabe is quieter than, say, the F-sport...but they both offer the -exact- same performance.

KI_GSE21

iTrader: (5)

I agree with you that technology is definately moving forward. I think modern cats are still relatively restrictive. Japanese Tuners for the new GTR R35 have developed cat-deletes for the car (aka downpipe) that eliminates the factory cats. Companies like Mine's Japan, Amuse PowerHouse, J's Racing have created straight pipes that eliminate cats. These tuners are experienced and knowledgeable in extracting power from engines. There are also companies that developed "high flow cats."

And regarding the idea of drilled rotors, I still see the current C63 AMG, Porsche 911, and even the R35 GTR with the drilled rotors coupled with a performance caliper. It may not be practical/reliable to use in the long run compared to a blank/slotted rotors. However, I think there is a reason why those cars today are still equipped with the drill rotors setup.

Also, removing the factory exhaust and replacing it with a Tanabe or F-sport exhaust system is not all about increasing the noise levels. There is also an increase in the piping diameter, which allows exhaust fumes to evacuate quicker. Aftermarket exhausts are also designed to be lighter to reduce the total weight of the vehicle. When your car is lighter, it has better fuel economy and is also faster. However, this may only be important if you are taking the car to the track for a time attack where every second counts.

Kurtz

iTrader: (1)

That's great.

And yet when people have actually -measured- gains from removing the secondary cats on the actual car we're talking about, the 2IS, they gain 1-2 horsepower, exactly as I described. They're really NOT restrictive.

The GTR makes a whole ton more power though and does it with turbos...so that's hardly a useful comparison... plus, many companies that sell "high-flow" cats do so to people whose minds are still stuck in the late 70s when such mods were significant...again like the rotors...speaking of-

Yes, because the buyers are ignorant of how brakes actually work, but they "look cool" and it's what such buyers expect to see because all the expensive show cars have them. That doesn't make them any less inferior a rotor though. Likewise many cars come with an idiotic big wing on them that will do little to nothing for the average buyer... here at least a few higher-end models might be driven to where they'll get useful downforce, so it's a little better than the rotor issue...but it doesn't stop 10 times as many folks from putting on laughable big aftermarket wings on cars that gain nothing from them thinking it's doing something.

Nobody ever went broke selling to people who didn't know any better.




My point was that the louder exhaust (F sport) produced the -same- performance gain as the quieter one (tanabe)... disproving your earlier suggestion that louder automatically equals "greater/smoother exhaust flow"

KI_GSE21

iTrader: (5)

Haha, alright Kurtz, I guess what you said defeats the purpose of modifying cars since brakes, downforce, and exhaust systems are all useless. You have your point You're not wrong, it's just a matter of personal preference. I am not trying to "disapprove" your claims, just sharing my thoughts. It's all cool

I guess different people take different perspectives of tuning cars. I tune my car at AJ Racing and they've modified cars since the early 1990s and today they still take their cars to the track.

Kurtz

iTrader: (1)

I'm not suggesting modding brakes, downforce, or exhaust are useless.

I'm just suggesting that the specific ways of modding them discussed between you and I are, largely, useless. Drilled rotors actually make the brakes worse... wings, on most cars, just give something people to point and laugh at, though there are some cars they do produce useful downforce on (just not most of the ones that actually slap wings on)... and exhaust system mods can gain plenty of useful performance results... just not in the case of removing the cats on a 2IS, where they've been proven, again and again, to add no more than 1-2 hp.

Modding brakes on a race car however can, in some situations, certainly be useful to modify feel, compliance, control heat, reduce fade, etc... just none of those solutions are likely to involve drilled rotors.

Increasing downforce on a car, when you actually do some testing to measure it, and the car will routinely spend time in triple-digit speeds, can be quite useful.

And exhaust changes on cars with highly restrictive exhausts, or overly unrestrictive ones (ie the guy who puts a 4" exhaust on his 1.6L stock honda) can make significant changes. But modern cats are surprisingly high-flow right from the factory, to the point they rarely make much difference by removal other than noise and legality.


I've been modding cars longer than your buddies at AJ racing have, long enough in fact I remember when removing the cat(s) on a stock vehicle actually produced really useful gains...(pick just about anything US manufacturers built with a V8 and cats in the 70s for example) but I'm sure they're not building race cars out of stock ISx50s with just the cats removed either.

KI_GSE21

iTrader: (5)

Kurtz, thanks for sharing your thoughts about modding cars.

i3urton

joez pts true exhaust with race version....ftw look at the sticky in performance .. a cl member put all the exhaust into a nice lil tread for every one

MIA_LEX

iTrader: (4)

Borla has been purchased. Thank you all for your opinions!

i3urton

ahhh.. joez ftw. not just because i have it.

DaveMS

Which version did you purchase?

Cat Back #140236 (Keeps secondary cats)
Competition #140189 (Removes secondary cats)

I am curious if they have corrected the fitment issues.