yup! im excited!

 

Yeah.. I was excited too...

I was also confused when it was mentioned that "they are different"..

When all this time we are told they are the same???

My guess is the OEM ones are the same, but the aftermarket headers will have to be designed/sized just a bit different between the IS250 & IS350

Then I guess we will also have to wait & see how the O2 sim works, if the IS350 ends up throwing a CEL as well..

.

 

Daniel said early on that the 350 headers would have different sized primaries.

 

Oh well.. I missed that one I guess...

(a post from 3 1/2 months ago... )

 

https://www.clublexus.com/forums/sho...3&postcount=34

 

Properly sized primaries for the 250 would kill top end on the 350. It might still work and be more mid-low torquey, but top end would surely suffer compared to a properly sized primary.

 

what are you saying here?

 

Thank you for reading.

The OEM headers are exactly the same, my headers are different. The difference is in the collectors not the primaries. Early on my.is I mentioned that the Megas are huge for the 250 with their 1.75" primaries and that the 250 needs 1.25" primaries to make the most power. I unfortunately do not have tooling to bend that, so i went with 1.5" which is perfect for the 350 and again why I say, I have no dough the 350 will make huge numbers.

Also, technically, if the headers was made with 1.25" primaries for the 250 it would make even more power. This also goes for the IS300 which ideally needs the tube to be somewhere around 1.35 ID.

 

So if I got these in CA... would I have to find a "special place" to pass whatever inspection and smog? Also, would I have to start going to Exact instead of the Lexus dealership for service?

 

Yeah, unless you put the stock ones back on. As for Lexus, the only thing theyc an void as far as warranty is your exhaust warranty. That's it.

 

It wouldn't surprise me if Lexus denied warranty claims on more than just the exhaust (burned exhaust valves, wideband O2 sensors, etc.). They might also blame the extra radiant heat for failures of other nearby components (starter, etc.).

 

how do they differ in the collector? and how does that effect each one?

glad u have the tools for the 350 primary size. or should i say that it happens be a nice number

 

I can't say what the difference is in collectors, but each one is made to work correctly with the motor of the 250 or the 350.

 

Are you using a custom built collector or off-the-shelf from someone like Burns Stainless?

 

Two 3-1 collectors from Burns would probably cost more than the headers. :O