JDM ITR Header... restrictive?

[d336]

Hi i searched and couldn't a direct answer... I heard that although the JDM ITR header has a 2.5 inch collector, it can restrict flow when you get past 200 whp. One reason I heard is that the welds are on the inside of the collector as opposed to outside, making it not a true 2.5. Is that what restricts it? Thanks

[Us3rname]

Originally Posted by d336

Hi i searched and couldn't a direct answer... I heard that although the JDM ITR header has a 2.5 inch collector, it can restrict flow when you get past 200 whp. One reason I heard is that the welds are on the inside of the collector as opposed to outside, making it not a true 2.5. Is that what restricts it? Thanks

I dont know about restricting at 200whp but it gave my buddys b16 a little bit more

[IntegraXTR]

what do you have that gives you 200 hp?

i've seen that header on cars that made over 200.

it's a great header...for the price as well

[female four]

Originally Posted by d336

Hi i searched and couldn't a direct answer... I heard that although the JDM ITR header has a 2.5 inch collector, it can restrict flow when you get past 200 whp. One reason I heard is that the welds are on the inside of the collector as opposed to outside, making it not a true 2.5. Is that what restricts it? Thanks

Restrictive, no. Restrictive compared to a suctom header, maybe. It all depends on your definaition.

Comparing it to any other mass produced header out there though its probably your best bang for the buck. It has an OD of 2.5" so the ID is a lot smaller. But still larger than a 2" OD collector, which also means the ID of the 2" header is smaller.

When you are making that much power, its really dependent on header design and layout, not the welds itself. Of course a bad weld is not a good weld, but its probably one of the less things on your mind.

[d336]

Is the DC JDM header have a true 2.5?

[A_White_GS-R]

I currently have the jdm dc2 header on my car. 4-1 tubular with a 2.5 collector. Great header. The butt dyno loved it. It responded very well with the mods i had at the time which were the full list of boltons you know header intake exhaust manifold cat etc. Speaking with some experienced tuners and engine builders i am under the impression that my engine will now choke with the header. Engine has more now than just bolt ons. not exactly sure why it would "choke" on the dyno with this particular header. My estimated goals for the engine are the 200whp range and up. My header is dented underneath due to some "spirited driving in ny" aka pot holes. Looking into the rmf narrow version.


The itr header is a good one dont let anybody tell you its restrictive or anything like that. There are plenty of 200whp cars that run that header and do just fine.

[98civcEK]

Originally Posted by d336

Is the DC JDM header have a true 2.5?

they answered no. its outside diameter is 2.5 but the inside is a little smaller

[female four]

When they say 2.5" collector, they mean OD, not inside. Thats the general rule for every header. Unless they specify it being an ID measurement, you can almost bet its an OD measurement.

Many people have modified the JDM header into a long tube header. It has been done. But by that time, I'd probably just shell out the money for a long tube header.

[d336]

Originally Posted by 98civcEK

they answered no. its outside diameter is 2.5 but the inside is a little smaller

I meant DC sports replica of the JDM ITR header, I heard that it is actually ID 2.5. thanks for the answers guys

[female four]

Originally Posted by d336

I meant DC sports replica of the JDM ITR header, I heard that it is actually ID 2.5. thanks for the answers guys

No.

[d336]

Anyone have experience with the 5zigen JDM 4-2-1 header?