Originally Posted by AlOtaBblGm

If passing smog is important, be careful of "headers". A pet peeve of mine with the F aftermarket is when "installing headers" is mentioned for the IS F, it's not just headers- you are removing the primary cat also which is the majority of the freed up horsepower around stock levels which is also why you need a tune to remove the second O2 input. If I was to install headers wanted to still have a chance to pass visual smog, I would relocate the primary cat to the start of the midpipe section. And the zinger is after $k's, with the primary cats in, you will only gain a few hp at most. The cats are the main restriction.

Some folks love to bash the F headers but I suspect the truth is those cats needed to be right where they are. IMHO those headers are masterpieces of compromise. Mr. Yaguchi is no rookie and no company wants to spend money on things like that unless it is necessary to meet the overall goal of the car.

Originally Posted by LexusfanVA

I don’t recall who it was but 1-2 members on here did multiple dyno runs with catless headers and after adding high flow cats to their system and they still gained 80%+ of the gains of going strictly catless, with none of the smell and being able to pass inspection. The design is poor and part of the reason that RCF have more power and gain less with headers. Plus, they tend to crack.

Originally Posted by lobuxracer

Sit in an RC F. If you're 6' 2" like me, your head will be scraping the headliner unless it's a carbon model. The RC F isn't particularly utilitarian, so having it as a primary vehicle means you are unlikely to have it as your only ride. The price point isn't aimed at the young and single crowd, most of the folks spending RC F money have wives and families. The 2+2 configuration means there are a limited number of folks seriously considering one for anything more than something fun to play with.

I currently own (both since new) an '08 IS F and a '16 GS F. I have posted a number of times answering the question, "Which would you choose" from the perspective of someone who owns and drives both back to back. NSX7, you are on that thread as well.

https://www.clublexus.com/forums/gs-...f-to-gs-f.html

And this post is STILL dead accurate from my perspective: https://www.clublexus.com/forums/gs-...ml#post9794641

Originally Posted by ISF4life

Every driver is different, u have to drive the car to know what u like and dislike if modded. Most people would prefer stock so they can build to what they want I can tell you that, ISF is raw and nimble =athletic of all the F line up

Originally Posted by NSX7

I am not sure if I can call the IS F raw or nimble - I usually reserve both descriptions for something like the S2000

Originally Posted by NSX7

So if the design is poor, and it's a known fact in the IS F community, that would make the headers a definite upgrade and hence will not take away from the value of the car?

Originally Posted by AlOtaBblGm

Maybe this sums it up. This is my opinion:

If I want to spend a few grand, get 45 hp , and maybe not pass visual smog, go headers and tune
If I want to spend a few hundred, get 40 hp, and have a reasonable chance of passing smog, Cat cutout and tune
If I want to spend a few grand and a few hundred, maybe get 5 hp, and probably pass visual smog, get headers and relocate cats

Originally Posted by AlOtaBblGm

Maybe this sums it up. This is my opinion:

If I want to spend a few grand, get 45 hp , and maybe not pass visual smog, go headers and tune
If I want to spend a few hundred, get 40 hp, and have a reasonable chance of passing smog, Cat cutout and tune
If I want to spend a few grand and a few hundred, maybe get 5 hp, and probably pass visual smog, get headers and relocate cats

Originally Posted by flowrider

^^^^The primary catalytic converters are integral with the stock exhaust manifolds. I'm certain with enough money new hi-flows could be welded in place, but no one has done it. The reason - Cost prohibitive and headers with hi-flow cats mounted in the piping behind the headers are the best solution. However, some have drilled out the metals in the stock cats, which IMHO is not really a good ides. And, if you leave the stock exhaust in place there is a another set of secondary cats.

Not sure I understand what AlOtaBblGm was posting

Lou

Originally Posted by AlOtaBblGm

Lol. I was just posting my opinion on the three paths the OP could go. For the third option, my plan would be that any tech other than an IS-F expert and Smog **** combo looking underneath would see the factory primary cats (albeit moved down a little) and call it a day. This would be after they see factory exhaust manifolds from up top. I have never seen them bother to put a car on a lift.