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Discussion Starter · #1 · (Edited)
Group buy details here http://my.is/forums/f167/is250-header-group-buy-353714/#post5262315

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Everything seems to be good now. The CEL has not come on in the past 250 miles, the SIM is working great! They will go on sale in about a week and the new price is $780 with the SIM. If you want me to install them, I can do it for $300.

Also today, I drove about 120 miles on the freeway mostly in 6th, and got 34 MPG! If I can keep it up I will get over 400 miles out of this tank.
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Dyno from today:



As you can see after driving with it a bit the car made a little more power and a lot more tq. If there was a way to tune this thing I am sure it can make even more power and have a more flat curve.

The CEL is back, so i need to start thinking about how to get rid of it.

After seeing the final numbers I was able to pull out of the 250, I don't think I need to dyno the 350 to know it will make well over 30 whp and I would say over 40 wtq.

This also confirms how TU Wen or how ever you spell that companies name who makes headers for the IS250, was able to make 240 or so hp from their headers and full exhaust.

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After a few months I am ready to show the results.





The headers added 21 whp and a very nice 25 wtq on my 08 6speed 250. The peak numbers where 195whp and 182wtq on a DynaPack dyno. I don't have the dyno yet with me, I will post it tomorrow.

I am very happy with the results and I think all of you will love them, it makes the car a lot more fun to drive, not super fast or anything, but i nice addition down low and on the freeway. Sound wise it sound the same, maybe a little bit louder.

These will go on sale 02/01/08 and will be $650 for both models. The IS350 system is a bit different and I think the 350 will make over 30whp easy with these.

Daniel
 

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Bunch of questions, and I'm probably jumping the gun here. I presume you'll have more info closer to the available date but.......
-Are the results you posted with the stock exhaust? Does it bolt up directly?

-What gaskets are needed?

-o2 sim is obviously needed, is it included or available from you?

-How is install? I know its very tight in there, I presume you installed from the bottom. Anything special to be aware of? Is the steering shaft in the way? does install mandate removal of the steering shaft?
 

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Wow...beautiful work! And an excellent price.
 

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very good price!!
 

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Discussion Starter · #5 ·
Bunch of questions, and I'm probably jumping the gun here. I presume you'll have more info closer to the available date but.......
-Are the results you posted with the stock exhaust? Does it bolt up directly?

-What gaskets are needed?

-o2 sim is obviously needed, is it included or available from you?

-How is install? I know its very tight in there, I presume you installed from the bottom. Anything special to be aware of? Is the steering shaft in the way? does install mandate removal of the steering shaft?
Thanks guys!

- Yes all done with the stock exhaust.

- As far as I know there is no O2 sim for the new IS, I dynoed with the CEL on.

- It is very tight. The passenger side is easy, the driver side I had to un bolt the steering shaft to make it easier, but I think it can be done without unbolting it.

No tips really, just have to get creative with the bolts.
 

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very nice!
 

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This is very interesting. A 30hp gain for that price would be great. Keep us posted on the IS350 model. Thanks.

-Mike
 

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Not to sound too retarded, but what is the O2 sim? couldn't there just be a bung added so that the stock O2 sensor would just drop right in? that would be priceless I think. I'd be down to buy if there was a way to get rid of the CEL.
 

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Not to sound too retarded, but what is the O2 sim? couldn't there just be a bung added so that the stock O2 sensor would just drop right in? that would be priceless I think. I'd be down to buy if there was a way to get rid of the CEL.
ok o2 sensors read before and after the cat now if u take the cats out like with these headers do then u will throw a cel ok and a o2 sim simulates the signal to ur computer and it thinks the cats are there and takes the cel off


some tap in to o2 sensor and u must have the o2 in the exhaust stream

some u can pluge and not have the o2 sensor in the exhaust stream

but i don't think they make one for us

hope this helps
 

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Discussion Starter · #13 ·
I am not sure what to do about that. I am going to talk to the guy at o2sim.com see if they can help.
 

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is there no possibility of shortening them and adding a high flow cat (a la jun-tw) for around another $200? removing the second cat i don't hav ea problem with but i'm a little uneasy about the primary cat ... and the possibility of a cel light/o2 sensor issue.

also if you plan to add a cat back exhaust you'll probably have 0 cats. only resonators and mufflers to quiet the sound down...maybe the mufflers will just have a lot to do?
 

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Discussion Starter · #17 ·
is there no possibility of shortening them and adding a high flow cat (a la jun-tw) for around another $200? removing the second cat i don't hav ea problem with but i'm a little uneasy about the primary cat ... and the possibility of a cel light/o2 sensor issue.

also if you plan to add a cat back exhaust you'll probably have 0 cats. only resonators and mufflers to quiet the sound down...maybe the mufflers will just have a lot to do?
I am about performance and everything else after, so If you want to add CATs you can still do so at a muffler shop, there is a lot of room.
 

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I figured a lot of 2nd gen guys would be scared to drop this in due to a CEL.. In all honestly this is for performance gains primiarily not for convenience. If you want more power out of your 2nd gen IS, then either put up with the CEL, or don't bother at all.

For those wanting cats and resonators or whatnot, these can all be done at your local muffler shop.
 

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I am about performance and everything else after, so If you want to add CATs you can still do so at a muffler shop, there is a lot of room.
i'd be really interested in hearing a 350 with your headers and a secondary cat-less exhaust..twin resonators preferably. i'm wondering if you could remove all the cats and still tune the exhaust to be not too loud and not too much like a lawnmower
 

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I figured a lot of 2nd gen guys would be scared to drop this in due to a CEL.. In all honestly this is for performance gains primiarily not for convenience. If you want more power out of your 2nd gen IS, then either put up with the CEL, or don't bother at all.
I'm in it for the performance, but I still take my car to the lexus dealership for warranty work and I don't want any unnecessary grief for the CEL.

Also, Daniel, what do you think the CEL issue can be solved by adding a bung hole on the headers at the apprximate same distance from the manifold as is on the OEM manifold?

Also, how soon can I get a set of the headers?
 
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