Hey guys i just bought a 2012 lexus isf. I beleive it has cracked headers so want to go aftermarket since its a perfect oppurtunity to upgrade. I was originallu going to go with sikky headers because the price for the quality but they are discontinued. That being said i think i want to do it right and go with ppe headers instead i know they are expensive but i feel like they wluld be worth the price. Going to have them hooked up to stock exhaust first then upgrade to possibly a Joe-z full catback with mid pipe later down the road. Are ppe really worth it and if so should i go with equal or unequal length . I dont want to have to change them again so trying tp do a one and done please aby suggestions would be amazing !!!! .. wish i could afford novel but a full system is like 12k and thats way out my price range.

PPE are worth it. As to equal versus unequal, the only real difference is sound. Pick your favorite sound and you’ll be happy long term.

The PPE are very nicely made, I would avoid ebay OBX headers if at all possible.
Be prepared to spend ~$360 from an authorized denso parts dealer for primary O2 sensors, they are notorious for becoming seized in the stock manifold. (denso part# 234-9048)
For the starter there is a plastic shield that covers the power wire that will crumble and need to be replaced, (part# 82821-30730)
The starter is accessed by removing the passenger side header . I would say definitely consider replacing it depending on miles etc while the headers are out. (denso reman or one from lexus is probably best) Having said that I did headers at 100k didn't replace the starter and luckily, knock on wood, I haven't had any issues with the original starter yet 20k miles later
The PPE EL headers require the dipstick tube to be bent, PPE does sell a pre-bent tube that makes life a lot easier.

If you're close to Waco I have PPE EL w/ xforce varex you can take a listen to

PPE equal/unequal length you cant lose either way.

Besides sound, there is a slight pro for equal length.

Heres a direct quote from RR Racing's Site:

"An equal length header will expel gases at an equal rate per pulse, with gas from each cylinder leaving the header at the same time. With an unequal length header, gas from the two longer runners will remain in the header as it will take longer to reach the collector -- this results in lower cylinder temperature on an equal length header, which can help prevent ringland failure. Another benefit of equal length headers is the balance of backpressure at the exhaust ports, which will improve volumetric efficiency and overall top end performance."

With that being said, I have not dyno tuned my car yet but I will say I feel a very big difference from mid to high rpm from the stock configuration (feels like it keeps wanting to pull even at redline).

I havent rode in a UEL header ISF so im no sure where the powerband benefits the most in that set up.

Regarding sound, if you want a domestic v8 sound, go UEL. If you want a more JDM/Exotic tone, equal length is the way to go.



Heres my video of my set up: PPE Equal Length/Greddy Titanium

The only way to substantiate that claim is by measuring cylinder temperatures. It sounds plausible; but i have not seen any data from RR backing that up. Considering the numerous UEL headers on millions of cars, it would be a negligible difference at best. We discussed this in another thread some time ago, but I think it died as it seemed more speculation than fact. I’m happy to be wrong here, but the only documented difference is sound.

Thank you so much for info I will definitely consider replacing during install of the headers.. I have 90k miles currently so I'm trying to so everything right the first time if possible rather than trial and error. That is the glory of these forums So does PPE include the pre bent dipstick or is that something you have to purchase separately. Im actually in Dallas, I may be able to make a trip out that way maybe the end of the month unless you could DM me a sound clip !

From an engineering perspective it makes sense though. Equal exhaust pulses should (by design) keep cylinder temperatures down.

i did a quick google search "Equal vs Unequal Length Headers" and found a few sites explaining the difference between the two and lines up with what RR Racing is stating. Mind you, most of the information is geared towards the EJ motors (and some euros).

Whats interesting is the ringland failure that is mentioned alot in the subaru forums (specifically cylinder #4), I know for those going the supercharged route, that is always a topic of concern (maybe related to the header design from the factory?)

Either way, I believe the reason we dont see a huge disparity in motor conditions between the two configurations is because the 2UR is a very well-built engine. I know there are FBO F's running UEL at 200k+ miles that literally beat on their cars on a daily basis.

I do believe equal length is more efficient, but without a proper dyno and extensive engine diagnostics we can only agree to disagree LOL.

I definitely think considering the difference in price and the fact that I would like to have some wiggle room to do a full exhaust also im probably going to have to end up going with unequal length especially since im going for the cleaner v8 note and not so much raspy given this car will spend most of its time as a daily driver with definitely some frequent spirited driving but the car will get little to no track use. I just refuse to spend the same price on the same restrictive stock headers especially if regardless I can get some more power out of after market.

So i plan on getting the PPE headers through fig manufacturing since i don't think you can order through PPE directly. If i do headers first can i have them hooked up to stock exhaust for now until I have money for new exhaust and still be able to pass emissions? I was Told by figgs that I would need to find the 02 conditoners in order for it to pass emissions but that they no longer offer them for purchase. Do you happen to know which ones would be good to get. Im willing to pay for quality ones I just have no idea what im looking for?

Duplicate answer from other post with same question:

Get the RR tune and you won't have to deal with O2 conditioners and you should be able to pass emissions with no issues especially with the stock exhaust because your secondary cats will still be present and cleaning the exhaust stream

@MileHIFcar ahh i see but if i choose to upgrade the exhaust later on however will that loop hole still be able to work or i guess that would depend if I have the high flow cats welded in or not ?

Yes if you have the RR tune it will be fine as the tune makes the ECU read that the secondary O2's are reading correctly (with OEM catback OR aftermarket exhaust).

Did Fig's tell you that PPE is no longer shipping out the headers with O2 conditioners?

@MileHIFcar Yea unfortunately so.. they are trying to not get shut down. So how reliable is the RR Tune .... I really don't want to jeopardize the reliability which was my only reason of holding off on the tune. I wanted to see if basic bolt ons would be enough to do the trick for me.

I want to agree with you. I’m just noting that there is legit no proof or data to back this up. A big issue in the car scene is company’s making claims, or people online, without presenting empirical data. Few mods delivered on those claims. If there was proof they were more reliable or safer, I’d order them. I like their sound better than mine. The price difference is large though.

You will find a split camp here. Tuning this car has some questionable results. My car hated the tune. Runs like a champ now with O2 conditioners that are little more than a spacer. I sold my tuner to a member who loves it and thinks his car is faster now. Do thorough research and arrive at the conclusion that best fits your circumstances. I’ve talked to many like him that love the tune, and many like me that didn’t see any gains. I will note, the haters mostly had newer ISFs. Maybe the tuning strategy was different in those model years... I can’t find any answers there.

I honestly don't understand the huge price difference. Maybe the labor and cost in materials is the driving factor for the huge difference. Thats one thing I do not like about the F world, theres little to no support and/or data to show what really works and improves the performance on this car. It gets very frustrating at times being that its such a good platform that gets ignored because of its "rarity".