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I have found bits and pieces of information regarding these two sets of headers. Though I haven't found any conclusive, absolutely truthful information. Will someone please tell me:

1. Where and When the headers will be available for purchase
2. Quality, function, hp/tq gains (dyno gains not claimed gains)
3. Check Engine light functionality
4. What do they do with the primary and secondary cats?
5. Any other pertinent information you deem necessary for me to know.

Thanks a lot, and hopefully this will clear up a lot of random information for people so we can actually decide if we want to invest the money to install these on our cars! Thanks.
 

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I have found bits and pieces of information regarding these two sets of headers. Though I haven't found any conclusive, absolutely truthful information. Will someone please tell me:

1. Where and When the headers will be available for purchase
2. Quality, function, hp/tq gains (dyno gains not claimed gains)
3. Check Engine light functionality
4. What do they do with the primary and secondary cats?
5. Any other pertinent information you deem necessary for me to know.

Thanks a lot, and hopefully this will clear up a lot of random information for people so we can actually decide if we want to invest the money to install these on our cars! Thanks.
1. Both are out. I am offering my at a lower price for the 1st 10 orders http://my.is/forums/f167/is250-header-group-buy-353714/ you can get the Juns here L-Tuned Parts - Lexus Parts - Ultimate Store for Lexus ES300 ES330 GS300 GS400 GS430 GX470 IS300 LS400 LS430 LX450 LX470 RX300 RX330 SC300 SC400 SC430
2. Gains for mine can be seen here http://www.mazzurisuper.com/images/is250_dyno.jpg not sure where to find the Jun dyno.
3. I had a custom sim made to get rid of the CEL, not sure if the JUNs come with one.
4. My set gets rid of the promaty CATs, secondary are still there. Juns come with CATs.
5. Don't drink and drive!
 

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Discussion Starter #3
"Don't drink and Drive" Haha, thanks.

Well that just about covers it. No primary cats is not an option, because we here in Ohio have absolutely no vehicle inspection, I could run no cats but I don't because I like to hear myself think when I drive.

One more question, Who do you think could do the install?? Any custom exhaust shop or what?? It's not like an older car where you can reach in and pull out the old and put in the new. I can't even see the headers in this car, though I have never looked up from the bottom. Let me know. Thanks
 

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"Don't drink and Drive" Haha, thanks.

Well that just about covers it. No primary cats is not an option, because we here in Ohio have absolutely no vehicle inspection, I could run no cats but I don't because I like to hear myself think when I drive.

One more question, Who do you think could do the install?? Any custom exhaust shop or what?? It's not like an older car where you can reach in and pull out the old and put in the new. I can't even see the headers in this car, though I have never looked up from the bottom. Let me know. Thanks
Our car has 4 CATs and a very restrictive exhaust, because of that with the headers on, the car does not get any louder, it sounds 98% stock, just a bit louder during cold starts.

Any shop can install it, it's just time consuming a lot of stuff has to come out to get to the headers. It takes about 5 hours.
 

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Thanks for creating this thread... i've had the exact same thoughts as you. Anyone here running the JUN-TW exhaust manifold? What are your thoughts?

Seems like there's huge gains to be made whilst still utilizing the stock exhaust system.
 

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Thanks Danielm for the link to our site. I will answer as best as we know right now.

The Jun-TW headers are going to be here in about 6-8 weeks. We already have a set sold to a local customer, and are bringing in an extra set for stock. Jun-TW has stated to us that there are no CEL lights, but we will confirm that once we have installed a set.

The dyno info we have so far is 238HP/6200rpm on the IS250. Again, we have not yet confirmed the numbers, so we will be getting as much info as we can from the customer who is the the install locally.
 

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Discussion Starter #8
Those numbers are outstanding, with the JUN-TW.

But from what I can see now, the Mazurri's seem like the most likely candidate to win popularity. For one, the person creating them is deeply involved with the car owners via this forum and Club Lexus and is quite prompt to answer questions regarding his product. Secondly, his are considerably cheaper and with a 5 hr. install at a good shop running close to $500, the lower cost certainly carries much more weight when deciding.

We don't have very fast cars, and If i have to lose the possibility of not gaining as many horses versus dropping $1000, I feel it is worth it!!
 

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Thanks Danielm for the link to our site. I will answer as best as we know right now.

The Jun-TW headers are going to be here in about 6-8 weeks. We already have a set sold to a local customer, and are bringing in an extra set for stock. Jun-TW has stated to us that there are no CEL lights, but we will confirm that once we have installed a set.

The dyno info we have so far is 238HP/6200rpm on the IS250. Again, we have not yet confirmed the numbers, so we will be getting as much info as we can from the customer who is the the install locally.
No problem. I love the fact you guys always have the rare/hard to find stuff!!
 

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Those numbers are outstanding, with the JUN-TW.

We don't have very fast cars, and If i have to lose the possibility of not gaining as many horses versus dropping $1000, I feel it is worth it!!
Unless their Sim also tunes the car somehow (even with that it's not possible), there is no way they made 238 WHP out of the 250 with just headers (especially with the collectors they use and CATs), that's almost a 60 whp gain. I would say that's 238 at the flywheel, as in around 200 at the wheels, which is still great, but without seeing the before numbers doesn't mean much.

Again, nothing in life is 100%, but from my experiance a gain of 60 whp from just a header is almost impossible.
 

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Unless their Sim also tunes the car somehow (even with that it's not possible), there is no way they made 238 WHP out of the 250 with just headers (especially with the collectors they use and CATs), that's almost a 60 whp gain. I would say that's 238 at the flywheel, as in around 200 at the wheels, which is still great, but without seeing the before numbers doesn't mean much.

Again, nothing in life is 100%, but from my experiance a gain of 60 whp from just a header is almost impossible.
Yes, those JUN-TW numbers seem kind of funny. When I first looked at the claims I understood (By Mistake) that the 238HP number was performance of both the headers & full exhaust together. But I just had another look and they do seem to be separate performance numbers.

I am curious to see how the Jun-TW 'shorty?' headers with high-flow Cat's do against the Mazzuri type. Eventually I will have before and after dyno numbers for the Mazzuri type as I am in on the group buy. Probably someone else will have an independent evaluation before I get around to it though.

Regards,
 

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Follow-Up

Thanks Danielm for the link to our site. I will answer as best as we know right now.

The Jun-TW headers are going to be here in about 6-8 weeks. We already have a set sold to a local customer, and are bringing in an extra set for stock. Jun-TW has stated to us that there are no CEL lights, but we will confirm that once we have installed a set.

The dyno info we have so far is 238HP/6200rpm on the IS250. Again, we have not yet confirmed the numbers, so we will be getting as much info as we can from the customer who is the the install locally.
Luis, (We gotta have more cow-bell, baby.)

Do you have any feedback about the JUN-TW headers from your customer?

As it turns out, the set that Mazzuri made does not fit on the AWD cars like mine. Perhaps a AWD version will come around but its hard to say. What type of IS did your customer have? Any impressions so far? Can you buy the headers without the high-flow CATs or is it only a package deal?

Regards,
 

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Did Group buy ever happen?
Yes, the group buy happend but so did a bunch of other stuff afterwards.

My headers are still great and I am enjoying them very much. However, Mazzuri closed up shop so there is no more support on that end.

Regards,
 

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I got mine from the GB as well. Got over 20 hp to the wheel gain.---Dyno before and after to prove it. Cost me $650 to get them installed in Cincinnati. Noticable difference. Too bad they went out of business.
 
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